Active matrix substrate, method of manufacturing the same, and image sensor incorporating the same

ABSTRACT

A signal line and a pixel capacitor wire that doubles as a pixel capacitor electrode are fabricated parallel to each other from the same electrode layer through patterning thereof. Therefore, no additional steps are required to form the pixel capacitor wire. In such an arrangement, the pixel capacitor wire and the signal line are disposed parallel to each other; therefore, delays of signal transmission in the signal line and crosstalk between pixels are prevented from occurring. The active matrix substrate incorporating this arrangement is suitably used in liquid crystal display devices, image sensors, and the like. Similar advantages are available with an arrangement in which the signal line and the pixel capacitor wire are disposed parallel to each other, and the storage capacitor electrode, which will constitute a storage capacitor with the pixel electrode therebetween, and the scanning line are fabricated from the same electrode layer through patterning thereof.

This application is a divisional of application Ser. No. 09/520,609,filed Mar. 7, 2000 now U.S. Pat. No. 6,784,949, the entire content ofwhich is hereby incorporated by reference in this application.

FIELD OF THE INVENTION

The present invention relates to active matrix substrates for use in,for example, liquid crystal display devices and flat-panel-type imagesensors, and methods of manufacturing such substrates, and furtherrelates to image sensors incorporating such active matrix substrates.

BACKGROUND OF THE INVENTION

An active matrix substrate for use in, for example, a liquid crystaldisplay device is primarily constituted by electrode wires that aresignal lines and scanning lines disposed in a matrix, pixel electrodeseach provided for a pixel that is encircled by the signal lines and thescanning lines, and switching elements.

Each of the switching elements, if it is of a double terminal type, isconnected to one of the pixel electrodes as well as to either one of thesignal lines or one of the scanning lines, and if it is of a tripleterminal type, is connected to one of the pixel electrodes, one of thesignal lines, and one of the scanning lines. As the scanning linereceives a predetermined voltage signal, the switching element is turnedon, causing the image signal (electric potential) applied to the signalline to be transmitted to the pixel electrode. Well-known examples ofswitching elements for selectively driving pixel electrodes typicallyinclude TFT (Thin Film Transistor) elements of a triple terminal typeand MIM (metal-insulating film-metal) elements of a double terminaltype.

As shown in FIG. 9 through FIG. 11, in an active matrix substrateconstituting a part of a liquid crystal display device that includes TFTelements (hereinafter, will be referred to simply as TFTs) as switchingelements, the pixel is primarily constituted by electrode wires that aretwo signal lines 101 and two scanning lines 102 disposed in a matrix, apixel electrode 103 provided for a pixel area that is encircled by thesignal lines 101 and the scanning lines 102, and a TFT 104.

Note that FIG. 10 is a cross-sectional view taken along line F–F′ inFIG. 9 and that FIG. 11 is a cross-sectional view taken along line G–G′in FIG. 9.

The TFT 104 has a gate electrode 106 connected to one of the scanninglines 102, a source electrode 107 connected to one of the signal lines101, and a drain electrode 108 connected to the pixel electrode 103 andalso to one of two terminals (transparent electrode layer 112) of apixel capacitor (storage capacitor) 105 a which will be discussed later.As a scanning signal is coupled to the scanning line 102, it drives theTFT 104, causing an image signal (video signal) coupled to the signalline 101 to be transmitted through a source electrode 107 and a drainelectrode 108 and applied to the pixel electrode 103.

In the foregoing active matrix substrate, as shown in FIG. 11, the pixelcapacitor 105 a for storing the image signal applied to the pixelelectrode 103 is constituted by a gate insulation film 110, as well as apixel capacitor electrode (storage capacitor electrode) 105 and atransparent electrode layer 112 that are disposed opposing each otheracross a gate insulation film 110. The pixel capacitor electrode 105doubles as a pixel capacitor common wire (storage capacitor common wire)that commonly connects a plurality of the pixel capacitors 105 atogether that are located parallel to the scanning lines 102, and iscoupled to an opposite electrode on an opposite substrate (not shown)when incorporated in a liquid crystal cell.

FIG. 12( a) through FIG. 12( h) and FIG. 13( a) through FIG. 13( h)illustrate a manufacturing process of the active matrix substrate, wheregate electrodes 106 and pixel capacitor electrodes 105 are formed on aninsulating transparent substrate 109, and subsequently, a gateinsulation film 110, a semiconductor layer 111, a n⁺-Si layer(corresponding to source electrodes 107 and drain electrodes 108), atransparent conductive layer 112, a metal layer 113, a protection film114, an interlayer insulation film 115, and a transparent conductivelayer constituting pixel electrodes 103 are deposited and patterned inthis order. The transparent conductive layer 112 and the metal layer 113connected to the source electrodes 107 of the TFTs 104 constitute signallines 101.

In the active matrix substrate, the pixel electrode 103 is connected tothe drain electrode 108 of the TFT 104 through a contact hole 116 formedthrough the interlayer insulation film 115. Meanwhile, the pixelelectrode 103 (see FIG. 9) is separated from the signal lines 101 andthe scanning lines 102 by the interlayer insulation film 115, permittingthe pixel electrode 103 to overlap the signal lines 101 and the scanninglines 102 (see FIG. 9 and FIG. 10). It is known that this structureallows improvements on the aperture ratio and prevents insufficientalignment (disclination) from occurring in the liquid crystal, whichwould otherwise be caused by the shielding of the electric fieldgenerated by the signal lines 101 and the scanning lines 102.

Another typical, simpler method omits the step of forming the interlayerinsulation film 115 and the pixel electrodes 103 which is provided onthe film 115; the transparent conductive layer 112 is provided as pixelelectrodes, and a large aperture for a pixel is formed in the protectionfilm 114 which is deposited on the transparent conductive layer 112.This structure does not give as high an aperture ratio as the foregoingstructure, but enables the active matrix substrate to be fabricated by afewer steps and provides an advantage in terms of manufacturing costs.

The active matrix substrate prepared as above can find a wide range ofapplications which includes liquid crystal display devices. A specificexample is a photosensor, serving as a photodiode, constituted by asemiconductor-layer-deposited element formed on the pixel electrode 103so as to provide a PIN connection and a shot key connection; the pixelcapacitor (storage capacitor) 105 a of each pixel stores data in theform of electric potential as the diode increases its conductivity whereit is irradiated with light while applying a predetermined d.c. voltageto the other terminal of the diode.

Another example is a sensor for sequentially reading electric chargesthat are generated by an conversion layer provided in place of thephotodiode so as to directly convert light, x-ray, etc. to electriccharges and then stored in the pixel capacitor 105 a using a highvoltage. An embodiment is disclosed, for example, in Japanese Laid-OpenPatent Application No. 4-212458/1992 (Tokukaihei 4-212458; published onAug. 4, 1992) where each pixel stores in its pixel capacitor 105 a thoseelectric charges generated by the conversion layer as data in the formof electric charges (as data in the form of electric potential) inaccordance with the characteristics of an object. Similarly to a liquidcrystal display device, by sequentially scanning the scanning lines 102,for example, the data stored in a pixel selected through the scanninglines 102 is read and transmitted through an active element(corresponding to the TFT 104) to a data line (corresponding to thesignal line 101). At the other end of the data line, there is provided acircuit, such as an OP amplifier, for recovering a signal from the data;a set of image data is thus obtained from the object by the sensor.

The active matrix substrate, which is a precursor to the sensor in theforegoing example with no photodiode and no light-to-electricityconversion layer, can be manufactured at low costs without newinvestments in manufacturing tools and facilities, because themanufacturing process for liquid crystal display devices is applicableto sensors only by adjusting the dimensions of the pixel capacitor 105 aand the time constants of the active element so as to obtain optimalresults when used in a sensor.

For example, there is a demand for liquid crystal display devices usedas computer display elements (monitors) to handle an increasingly largeamount of information. To meet the demand, the display element (displaysection) is inevitably growing larger in size. Besides thoseapplications as computer monitors, larger liquid crystal display devicesare increasingly popular as monitors in AV (Audio Visual) and industrialsystems. Meanwhile, display elements of medium to small sizes areincreasingly required to produce highly clear images. In actualpractice, these tasks are hard to tackle by means of designs.

Referring to FIG. 9 through FIG. 11, the following description willexplain problems in solving the tasks more specifically. As the signallines 101 and the scanning lines 102 are extended in response to thegrowing size of the display element, signal delays in the wires becomeno longer ignorable. Meanwhile, in medium to small sized displayelements, the wires (signal lines 101 and scanning lines 102) inevitablycome to have great resistance as the wires are scaled down in breadth toensure a high aperture ratio with the already narrow pitches remainingunchanged, which results in more signal delays.

The problem of signal delays can be effectively solved by reducing theelectrostatic capacity between wires, which is another factor todetermine signal delays in the wires. However, the gate insulation film110, which separates the signal lines 101 from the scanning lines 102,has further functions to decide the properties of the TFTs 104 and toconstitute the pixel capacitors 105 a; therefore, we cannot readilyaccept the use of a thinner gate insulation film 110 to reduce theelectrostatic capacity per unit area.

The active matrix substrate for use in a sensor needs to clear morestrict standards than the active matrix substrate for use in a liquidcrystal display device; namely, noise, as well as signal delays,presents a problem that cannot be overlooked. Specifically, referring toFIG. 9 through FIG. 11, the pixel capacitor electrode 105, upon readinga signal from a target pixel, also receives a signal from an adjacentpixel that is connected commonly to the pixel capacitor electrode 105,which behaves as a noise superimposed on the target signal. Resolutionis degraded by the noise, i.e., the signal obtained from the adjacentpixel, interfering with the target signal due to the electrostaticcapacity between the pixel capacitor electrode 105 and the target pixelelectrode 103. Alternatively, the electrostatic capacity between thepixel capacitor electrode 105 and the signal line 101 behaves as a noisein the signal line 101, and amplified by an amplifier for detecting thetarget signal, raising an obstruction in getting correct data. To obtainhighly precise and accurate signals, the data is typically stored ingreater amounts without causing an unnecessarily great increase in thepixel electric potential. This is effectively realized by setting thepixel capacitor to a great value; however, that setting would increasethe impedance of a pixel capacitor common wire, resulting in aggravationof the aforementioned problems.

A more detailed explanation is given in the following about reasons thatthe impedance of a pixel capacitor common wire needs to be kept at a lowvalue. In a case where the scanning line is disposed parallel to thepixel capacitor common wire, at an instant when the scanning line for acertain line is selected, all the pixels connected by means of electriccapacity to the pixel capacitor common wire for that line behave as aload to the pixel capacitor common wire. In other words, in both casesof writing electric charges to a pixel and reading electric charges froma pixel, at an instant when the scanning line for a certain line isselected, the electric potentials of the pixels corresponding to thescanning line and the pixel capacitor common wire change all together,and therefore the electric potential of the pixel capacitor common wireconstituting electrostatic capacitors with the pixels oscillates orshifts greatly off the value at which the electric potential of thepixel electrode common wire is desirably maintained. The electricpotential of the pixel electrode common wire, if oscillates or shifts,can interfere with data, i.e., the electric potentials, for the pixelsand thereby cause crosstalk.

Further, if the pixel electrode common wire crosses, and are connectedby means of electric capacity to, numerous signal lines, the oscillatingor shifting electric potential of the pixel electrode common wirenegatively affects signals flowing through the signal line. Thephenomenon is particularly manifest with liquid crystal display deviceswhere the numerous signal lines are driven by high frequency alternatingcurrent.

For these reasons, in order to avoid negative effects on the electricpotentials of the pixels and the signals flowing through the signal lineand to stabilize the electric potential of the pixel capacitor commonwire, the impedance of the pixel capacitor common wire needs to be keptat an extremely low value. This is achieved by, for example, composingthe pixel capacitor common wire of a material of a small resistance.

Accordingly, a structure was conceived in which pixel capacitor commonwires are disposed parallel to signal lines, whereas pixel capacitorcommon wires are disposed parallel to scanning lines in a typicalstructure. FIG. 14 and FIG. 15 illustrate, as an example, such astructure of an active matrix substrate for use in an x-ray sensor asdisclosed in SID 98 DIGEST on pages 371 to 374. In the example, eachpixel is surrounded by signal lines 201 and scanning lines 202 that aredisposed in a matrix, and is provided with a pixel capacitor 205 a inwhich a pixel electrode 203 opposes a pixel capacitor electrode 205across a gate insulation film 210 b. Further, pixel capacitor commonwires 205 b are disposed parallel to the signal lines 201.

In the foregoing structure, the signal lines 201 do not cross the pixelcapacitor common wires 205 b; therefore, the electrostatic capacity(load capacity) on the signal lines 201 can be decreased. The impedanceof the pixel capacitor common wires 205 b can also be decreased. As aresult, the signal delays that occur in the signal lines 201 can begreatly diminished. In addition, crosstalk, which often raises a problemin a display device, can be prevented from happening. The structure, ifadopted in an active matrix substrate for use in a sensor, can preventthe degradation in resolution caused by the noise generated by data froman adjacent pixel. Specifically, when a certain line is selected (a rowof pixels parallel to the scanning line 202 to which a scanning signalis coupled so as to turn on the TFT 204 are selected) by means of ascanning line 202, the noise generated in the pixel capacitor commonwire 205 b may propagate along the signal line 201, but does notpropagate along the scanning line 202, affecting no pixels connected tothat scanning line 202. Therefore, the data obtained through the targetpixel is free from negative effects from the other, simultaneouslyselected pixels.

However, to manufacture an active matrix substrate structured as above,additional steps should be included in the manufacturing process of anactive matrix substrate shown in FIG. 12( a) through FIG. 12( h) andFIG. 13 (a) through FIG. 13 (h) before the formation of the pixelcapacitor common wires 205 b between the step of forming the scanninglines 202 (corresponding to those steps shown in FIG. 12( a) and FIG.13( a)) and the step of forming the gate insulation film 210 b(corresponding to those steps shown in FIG. 12( b) and FIG. 13( b)):namely, the additional steps are (a) the step of forming (depositing,patterning by photolithography, and etching) a transparent electrodefilm that is provided as the pixel capacitor electrodes 205 opposing thepixel electrodes 203 across the gate insulation film 210 b, (b) the stepof forming an underlying gate insulation film 210 a prior to theformation of the pixel capacitor electrode 205, and (c) the step ofdepositing, patterning by photolithography and etching the gateinsulation film 210 b so as to form a contact section 205 c between thepixel capacitor common wire 205 b made of metal and the pixel capacitorelectrode 205. Further, the gate insulation film 210 b needs to bepatterned for each pixel, separately from the other pixels; thisrequires a high level of precision in the patterning which can beachieved only through the use of costly photomasks and precise controlof conditions in exposure to light and etching.

No protection film (corresponding to, for example, the protection film114 in FIG. 10) is provided to protect the TFT 204; however, to improvethe reliability of the device, such as an x-ray sensor, an inorganicprotection film is preferably interposed between the TFT 204 and aninterlayer insulation film 215 typically constituted by an organic film.In actual practice, an inorganic film composed of silicon nitride, forexample, is interposed in the active matrix substrate for use in aconventional device. Consequently, the same number of steps are requiredafter the completion of the formation of the gate insulation film 210 bas in the conventional method shown in FIG. 9.

Therefore, the total cost will increase by the addition of the steps ofdepositing and patterning the transparent electrode film that will serveas the pixel capacitor electrodes 205, the addition of the steps ofdepositing and patterning (etching) the gate insulation film 210 b, andthe additionally required precision in the patterning of the gateinsulation film 210 b. Besides, if viewed in the balance with massproduction, we cannot benefit a lot from the adoption of the aboveprocess and an resultant increase in the number of steps in themanufacture of active matrix substrates of small to medium sizes wheredesign rules are relatively simple: the adoption would create anotherproblem of reduced productivity of the manufacturing line because of theneed for the manufacturing line to be adjusted so as to handle variousprocesses depending on the sizes of active matrix substrates.

Besides, if the pixel capacitor electrodes 105 are provided below thegate insulation film 110 as shown in the arrangement shown in FIG. 10and FIG. 11, a simple method of providing a transparent conductive layer112 as pixel electrodes become applicable as previously mentioned,except the step of forming the interlayer insulation film 115 and thepixel electrodes 103 thereon. By contrast, if the pixel capacitor commonwires 205 b are provided on the gate insulation film 210 b as shown inthe arrangement shown in FIG. 14 and FIG. 15, such an simple methodcannot be applied.

Further, in the active matrix substrate shown in FIG. 14 and FIG. 15, athrough hole which is large enough to form a supplementary capacitor isprovided in the interlayer insulation (polymer) film 215 that isdeposited in a thickness of 2 μm or more; if such an active matrixsubstrate is used in a liquid crystal display device, since the throughhole is located in an important part for image display (the part wherelight passes in the case of a liquid crystal display device of atransparent type), the through hole disturbs alignment of the liquidcrystal. Therefore, contrast degradation and other serious problems interms of display quality are highly likely to occur.

Meanwhile, U.S. Pat. No. 5,182,620 (corresponding to Japanese Laid-OpenPatent Application No. 3-288824/1991 (Tokukaihei 3-288824), published onDec. 19, 1991) discloses an active matrix substrate including TFTs of atop gate structure (normal stagger structure) as switching elements,wherein pixel electrodes are disposed on an interlayer insulation filmto achieve a high aperture ratio, and supplementary capacitor wires aredisposed parallel to signal lines. Besides, the semiconductor layer ofTFTs and the lower electrodes constituting capacitors are fabricatedfrom a polycrystalline silicon thin film through patterning and othersteps. Gate bus wires, gate electrodes, and upper electrodesconstituting capacitors are also fabricated from a polycrystallinesilicon thin film through patterning and other steps. Each of thesupplementary capacitor is formed by providing a lower electrodeconstituting the capacitor so as to oppose an upper electrodeconstituting the capacitor across an insulation film.

However, the arrangement cannot be applied to an active matrix substratewith TFTs of an amorphous silicon type for the following reasons. If atleast either of the lower and upper electrodes constituting a capacitorare formed from amorphous silicon, stable capacity properties are notavailable due to the replacement of the polycrystalline silicon thinfilm for an amorphous silicon thin film. More specifically, amorphoussilicon has a lower conductance than polycrystalline silicon, and thecapacity is more likely to be changed by voltage in a TFT of anamorphous silicon type.

Besides, an active matrix substrate including TFTs of an amorphoussilicon type better restrains leak currents from TFTs caused by lightprojection onto the active matrix substrate, if the TFTs are of aninverted stagger structure, instead of a normal stagger structure.

SUMMARY OF THE INVENTION

In order to solve the foregoing problems, the present invention has anobject to offer an active matrix substrate capable of preventing signaltransmission delays in signal lines and crosstalk between pixels withoutan increase in the number of manufacturing steps, and to offer a methodof manufacturing such an active matrix substrate. The present inventionhas another object to offer an image sensor incorporating such an activematrix substrate.

An active matrix substrate in accordance with the present invention, inorder to achieve the objects, includes:

a pixel electrode provided for each pixel constituted by a scanning lineand a signal line that are disposed in a matrix as a whole;

a switching element located near a point where the scanning line crossesthe signal line, so as to be connected to the scanning line, the signalline, and the pixel electrode;

a storage capacitor electrode for constituting a storage capacitor withthe pixel electrode therebetween; and

a storage capacitor common wire disposed parallel to the signal line,wherein

the signal line, the storage capacitor electrode, and the storagecapacitor common wire are fabricated from a single electrode layerthrough patterning thereof.

With the arrangement, the signal lines can be fabricated concurrentlywith the storage capacitor electrodes and the storage capacitor commonwires; therefore, the active matrix substrate can be manufactured withits storage capacitor common wires disposed parallel to the signal linewithout an increase in the number of manufacturing steps or in themanufacturing cost of the active matrix substrate.

More specifically, for example, a conventional manufacturing line forliquid crystal display devices (in which the signal lines cross thestorage capacitor common wires at right angles) can be used withoutmodifying the process in order to manufacture high-performance activematrix substrates for use in liquid crystal display devices, sensors,and the like; therefore, no investment is required for new equipment andtools and the productivity of the line is no likely to decline.

Besides, if the active matrix substrate of such a structure is used in,for example, a liquid crystal display device, image sensor, or othersimilar devices, the signal lines cross the scanning lines alone (inother words, the signal lines do not cross the storage capacitor commonwires); therefore noise and delays in signal transmission can beeffectively prevented. Pixels are hence charged quickly. Further, sincethe switching elements connected to pixels that share a single storagecapacitor common wire do not simultaneously turned on, crosstalk can beprevented.

That is, active matrix substrates can be manufactured that are capableof preventing delays in signal transmission from occurring in signallines and crosstalk from occurring between pixels without an increase inthe number of steps.

As laid out above, the active matrix substrate in accordance with thepresent invention can prevent delays in signal transmission in signallines because of a relatively low time constant of the signal lines,which is derived from the electrostatic capacity between the signallines and the other wires that is reduced by the signal lines crossingnone of the storage capacitor common wires unlike in conventional activematrix substrates.

Incidentally, as is often found in conventional liquid crystal displaydevices, a signal of a constant amplitude and 180° out of phase with thesignal supplied to the signal lines is in some cases supplied to thestorage capacitor common wires and the opposite electrodes that aredisposed opposing the pixel electrodes in order to reduce the amplitudeof the signal supplied to the signal lines. When this is the case,signal delays in the storage capacitor common wires are another problem.

However, since so-called floating gate drive is carried out whereby asignal of an identical amplitude to, and in phase with, the signalsupplied to the storage capacitor common wires is superimposed on theoff electric potential of the scanning lines; therefore, the voltagedifference between the scanning lines and the storage capacitor commonwires is always constant in a case in accordance with the presentinvention.

In other words, no capacitor components other than a stray capacitycontribute to an increase in the time constant of the storage capacitorcommon wires; therefore, the invention has an advantage that there aresubstantially no signal delays in the storage capacitor common wires.

Note that the storage capacitor electrodes and the storage capacitorcommon wires may be fabricated from the same electrode layer throughpatterning thereof so that the storage capacitor common wiresinterconnect the storage capacitor electrodes of adjacent pixels, or maybe fabricated so that each of the storage capacitor common wires iscommonly connected to a plurality of pixels and provided on the storagecapacitor electrodes that are formed individually for each of theplurality of pixels.

In the former event, if the signal lines have a single layer structure,the signal lines, the storage capacitor electrodes, and the storagecapacitor common wires can be fabricated from the same electrode layerthrough patterning thereof. In the latter event, if the signal lineshave a double layer structure, the signal lines, the storage capacitorelectrodes, and the storage capacitor common wires can be fabricatedconcurrently by fabricating the storage capacitor electrodes and thelayer below the signal lines from the same electrode layer throughpatterning thereof and fabricating the storage capacitor common wiresand the layer on the signal lines from the same electrode layer throughpatterning thereof; therefore, the foregoing advantages of the presentinvention are still available.

Another active matrix substrate in accordance with the present inventionincludes:

a pixel electrode provided in each pixel area bounded by a scanning lineand a signal line that are disposed in a matrix as a whole;

a switching element connected to the scanning line, the signal line, andthe pixel electrode;

a storage capacitor electrode for constituting a storage capacitor withthe pixel electrode therebetween; and

a storage capacitor common wire disposed parallel to the signal line soas to be connected to the storage capacitor electrode, wherein

the signal line and the storage capacitor electrode may be fabricatedfrom a single electrode layer through patterning thereof.

As laid out above, the storage capacitor electrodes and the storagecapacitor common wires may be fabricated from the same electrode layerthrough patterning thereof so that the storage capacitor common wiresinterconnect the storage capacitor electrodes of adjacent pixels, or maybe fabricated so that each of the storage capacitor common wires iscommonly connected to a plurality of pixels and provided on the storagecapacitor electrodes that are formed individually for each of theplurality of pixels.

In either event, if the signal lines and at least the storage capacitorelectrodes are fabricated from the same electrode layer throughpatterning thereof, conventional manufacturing steps can be used as theyare and the same advantages are still available.

A further active matrix substrate in accordance with the presentinvention, in order to achieve the objects, includes:

a pixel electrode provided in each pixel area bounded by a scanning lineand a signal line that are disposed in a matrix as a whole;

a switching element connected to the scanning line, the signal line, andthe pixel electrode;

a storage capacitor electrode for constituting a storage capacitor; and

a storage capacitor common wire disposed parallel to the signal line soas to be connected to the storage capacitor electrode, wherein

the storage capacitor is formed between the pixel electrode and thestorage capacitor electrode, and

the scanning line and the storage capacitor electrode may be fabricatedfrom a single electrode layer through patterning thereof.

The arrangement offers the same advantages as those derived from theactive matrix substrate characterized by the inclusion of the signallines, the storage capacitor electrodes, and the storage capacitorcommon wires that are fabricated from a single electrode layer throughpatterning thereof.

Specifically, since the signal lines have smaller electrostaticcapacitors, the S/N ratio improves, and the signal lines cause smallersignal delays. Besides, since crosstalk of signals in the storagecapacitor common wires can be prevented from degrading resolution, andthe load on the storage capacitor common wires is greatly reduced,little work is needed in design to reduce the impedance of the storagecapacitor common wires to improve on the precision of signals.

Besides, the active matrix substrate in accordance with the presentinvention is extremely advantageous in terms of cost, since aconventional manufacturing device for active matrix substrates for usein liquid crystal display devices can be used only with slightmodification in pattern design.

Besides, the active matrix substrate in which the scanning lines and thestorage capacitor electrodes constituting storage capacitors with thepixel electrodes are fabricated from the same layer is advantageous whenit is used in an image sensor of a large pixel capacitor byincorporating expanded storage capacitor electrodes, since the aperturearea of the pixel electrodes formed by providing a conversion layer onthe pixel electrodes is not affected by a possible light blockingproperty of the storage capacitor electrodes owing to the formation ofthe pixel electrodes on the insulation film subsequently to theformation of the scanning lines and the storage capacitor electrodes.

An image sensor having a large pixel capacitor value can efficientlycollect the electric charges generated by the projection of an x-rayonto the conversion layer, and prevent inconveniences such as electriccharges leaking from a switching element due to an abnormally increasedpixel electric potential or a broken switching element per se.

Alternatively, the pixel electrode, constituting a storage capacitorwith the storage capacitor electrode therebetween, may be replaced witha conductive body layer provided separately from the pixel electrode sothat the conductive body layer and the storage capacitor electrodesandwich the insulation layer (e.g., gate insulation layer).

In other words, the active matrix substrate in accordance with thepresent invention may include:

a pixel electrode provided in each pixel area bounded by a scanning lineand a signal line that are disposed in a matrix as a whole;

a switching element connected to the scanning line, the signal line, andthe pixel electrode;

a storage capacitor electrode for constituting a storage capacitor; and

a storage capacitor common wire disposed parallel to the signal line soas to be connected to the storage capacitor electrode, wherein

the active matrix substrate further includes a conductive layer providedso that the conductive layer and the storage capacitor electrodesandwich an insulation layer,

the storage capacitor is formed between the conductive layer and thestorage capacitor electrode, and

the scanning line and the storage capacitor electrode are fabricatedfrom a single electrode layer through patterning thereof.

The active matrix substrate arranged in accordance with the presentinvention is suitable when the switching element has a bottom gatestructure.

Further, the active matrix substrate arranged in accordance with thepresent invention is suitable when the switching element is a thin filmtransistor of an amorphous silicon type (TFT of an a-Si type).

Still another active matrix substrate in accordance with the presentinvention, in order to achieve the objects, includes:

a pixel electrode provided in each pixel area bounded by a scanning lineand a signal line that are disposed in a matrix as a whole;

a switching element connected to the scanning line, the signal line, andthe pixel electrode;

a storage capacitor electrode for constituting a storage capacitor withthe pixel electrode therebetween; and

a storage capacitor common wire disposed parallel to the signal line soas to be connected to the storage capacitor electrode, wherein

the scanning line and the pixel electrode may be fabricated from asingle electrode layer through patterning thereof.

The arrangement offers the same advantages as those derived from theactive matrix substrate characterized by the inclusion of the signallines, the storage capacitor electrodes, and the storage capacitorcommon wires that are fabricated from the same electrode layer throughpatterning thereof.

In addition, after depositing a gate insulation film on the layerconstituted by the scanning lines and the pixel electrodes, forming theswitching elements, the signal lines, the storage capacitor electrodes,and the storage capacitor common wires, and forming a protection film,the protection film and the gate insulation film can be concurrentlypatterned using the same photomask and the like to form aperturesections in the pixel electrodes.

Therefore, when the scanning lines and the pixel electrodes arefabricated from the same electrode layer through patterning thereof asin the foregoing, the use of the single photomask and the patterning ofthe protection film and the gate insulation film in a single stepresults in combination in reducing manufacturing cost by great amounts.

In addition, the pixel electrodes are kept protected by the gateinsulation film up to the step of patterning the protection film;therefore, the surfaces of the pixel electrodes are hardly contaminated.As a result, if a conversion layer is deposited on an active matrixsubstrate of such an arrangement so as to constitute an image sensor,the conversion layer can be deposited on the aperture sections in thepixel electrodes in a stable manner; therefore, the image sensor showshigh performance and gives good yields in manufacture.

Another active matrix substrate in accordance with the presentinvention, in order to achieve the objects, includes:

a first pixel electrode provided for each pixel area bounded by ascanning line and a signal line that are disposed in a matrix as awhole;

a switching element connected to the scanning line, the signal line, andthe first pixel electrode;

a second pixel electrode connected to the first pixel electrode;

a storage capacitor electrode for constituting a storage capacitor withthe second pixel electrode therebetween; and

a storage capacitor common wire disposed parallel to the signal line soas to be connected to the storage capacitor electrode, wherein

the scanning line and the second pixel electrode may be fabricated froma single electrode layer through patterning thereof.

The arrangement offers the same advantages as those derived from theactive matrix substrate characterized by the inclusion of the signallines, the storage capacitor electrodes, and the storage capacitorcommon wires that are fabricated from the same electrode layer throughpatterning thereof.

In addition, the second pixel electrodes require only a small area whenno large storage capacitors are required; therefore, even if the secondpixel electrodes are formed from a metal or other light blockingmaterial as are the scanning lines, the light blocking area can beminimized. Further, since the first pixel electrodes can be formed fromITO (Indium Tin Oxide) or other light passing materials, the activematrix substrate incorporating such pixel electrodes is suitably used ina liquid crystal display device of a transparent type which has largeaperture sections. Further, since ITO or other such materialsconstituting the first pixel electrodes is stable, when the activematrix substrate of the foregoing arrangement is used to constitute animage sensor, a conversion layer can be deposited on the first pixelelectrodes in a stable manner.

Besides, when the conversion layer needs to be refreshed throughprojection of light, since the light blocking area is minimized as laidout above, a sufficient amount of light can be projected on theconversion layer from a desired direction.

A method of manufacturing an active matrix substrate in accordance withthe present invention, in order to achieve the objects, is a method ofmanufacturing an active matrix substrate arranged in the foregoingmanner, and includes the step of fabricating the signal line, thestorage capacitor electrode, and the storage capacitor common wire froma single electrode layer through patterning thereof.

According to the method, the storage capacitor electrodes and thestorage capacitor common wires can be formed concurrently with thesignal lines; therefore, active matrix substrates can be manufacturedthat include storage capacitor common wires parallel to signal lineswithout an increase in the number of steps. Specifically, for example, aconventional manufacturing line for liquid crystal display devices (inwhich the signal lines cross the storage capacitor common wires at rightangles) can be used without modifying the process in order tomanufacture high-performance active matrix substrates for use in liquidcrystal display devices, sensors, and the like; therefore, no investmentis required for new equipment and tools and the productivity of the lineis no likely to decline.

Another method of manufacturing an active matrix substrate in accordancewith the present invention, in order to achieve the objects, is a methodof manufacturing an active matrix substrate including:

a pixel electrode provided in each pixel area bounded by a scanning lineand a signal line that are disposed in a matrix as a whole;

a switching element connected to the scanning line, the signal line, andthe pixel electrode;

a storage capacitor electrode for constituting a storage capacitor withthe pixel electrode therebetween; and

a storage capacitor common wire disposed parallel to the signal line soas to be connected to the storage capacitor electrodes, and includes thesteps of:

depositing an electrode layer on the active matrix substrate andpatterning the electrode layer so as to fabricate the scanning line andthe pixel electrode;

depositing a gate insulation film;

fabricating the signal line, the switching element, the storagecapacitor electrode, and the storage capacitor common wire, andsubsequently depositing a protection film; and

concurrently patterning the gate insulation film and the protection filmso as to form an aperture section in the pixel electrode.

With the arrangement, the conventional steps of manufacturing an activematrix substrate are applicable without modification, including the stepof forming the scanning lines in which the pixel electrodes are formedconcurrently. Therefore, a conventional manufacturing line for liquidcrystal display devices (in which the signal lines cross the storagecapacitor common wires at right angles) can be used without modifyingthe process in order to manufacture high-performance active matrixsubstrates for use in liquid crystal display devices, sensors, and thelike, that include storage capacitor common wires disposed parallel tosignal lines; therefore, no investment is required for new equipment andtools and the productivity of the line is no likely to decline.

In addition, after depositing a gate insulation film on the layerconstituted by the scanning lines and the pixel electrodes, forming theswitching elements, the signal line, the storage capacitor electrode,and the storage capacitor common wires, and forming a protection film,the protection film and the gate insulation film can be concurrentlypatterned using the same photomask and the like to form aperturesections in the pixel electrodes. Therefore, the use of the samephotomask and the patterning of the protection film and the gateinsulation film in the same step results in combination in reducingmanufacturing cost by great amounts.

In addition, the pixel electrodes are kept protected by the gateinsulation film up to the step of patterning the protection film;therefore, the surfaces of the pixel electrodes are hardly contaminated.As a result, a conversion layer can be deposited on the aperturesections in the pixel electrodes in a stable manner so as to form animage sensor; therefore, the image sensor shows high performance andgives good yields in manufacture.

An image sensor in accordance with the present invention, in order toachieve the objects, includes:

an active matrix substrate having the foregoing arrangement;

a conversion section for converting incident magnetoelectric radiationto electric charges; and

bias voltage application means for causing a storage capacitor to storethe electric charges.

With the arrangement, the magnetoelectric radiation received by theimage sensor is converted by the conversion section into electriccharges which are subsequently stored in an electrostatic capacitor(storage capacitor). In a typical image sensor, requirements on thestorage capacitor and noise are very demanding. An image sensorincluding the foregoing active matrix substrate is capable ofrestraining them sufficiently so as not to affect properties of read-outsignals from an electrostatic capacitor. Besides, no additional stepsare required to form the active matrix substrate constituting the imagesensor. Besides, a conventional manufacturing line for liquid crystaldisplay devices (in which the signal lines cross the storage capacitorcommon wires at right angles) can be used without modifying the processin order to manufacture active matrix substrates constituting imagesensors; therefore, no investment is required for new equipment andtools and the productivity of the line is no likely to decline inproduction of image sensors.

Besides, if an active matrix substrate is used in which the storagecapacitor electrodes are fabricated from a transparent electrode film,the light blocking area can be reduced in size between the transparentsubstrate and the conversion layer in the image sensor; therefore, theconversion layer can be refreshed efficiently by the method ofprojecting light to the entirety of the image sensor.

Further, if an active matrix substrate is used in which the storagecapacitor common wires, as well as the storage capacitor electrodes, arefabricated from a transparent electrode film, the light blocking areacan be further reduced in size; therefore, the foregoing effect isenhanced.

Further, if an active matrix substrate is used that includes such anarrangement that the pixel electrodes are disposed opposing the storagecapacitor electrodes across the insulation film covering the switchingelements, image sensors can be manufactured without additional steps. Ifan active matrix substrate is used that includes the foregoingarrangement as well as such an additional arrangement that an interlayerinsulation film is interposed between the pixel electrodes and theinsulation film, and the pixel electrodes are disposed opposing thestorage capacitor electrodes in contact holes formed through theinterlayer insulation film, image sensors can be manufactured that havereduced affection between the pixel electrodes and the electrode lines(referring to the scanning lines, the signal lines, the connectionelectrodes, and other electrode wires disposed below the pixelelectrodes) and that can control the value of storage capacitors veryprecisely.

For a fuller understanding of the nature and advantages of theinvention, reference should be made to the ensuing detailed descriptiontaken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view showing an arrangement of an activematrix substrate of an embodiment in accordance with the presentinvention.

FIG. 2 is a cross-sectional view of the active matrix substrate shown inFIG. 1, taken along line A–A″.

FIG. 3( a) through FIG. 3( h) are cross-sectional views showingmanufacturing steps of the active matrix substrate shown in FIG. 1,taken along line A–A″.

FIG. 4 is a cross-sectional view of an active matrix substrate ofanother embodiment in accordance with the present invention.

FIG. 5 is a schematic plan view showing an active matrix substrate thatconstitutes a major part of an x-ray sensor of a further embodiment inaccordance with the present invention.

FIG. 6 is a cross-sectional view showing the x-ray sensor shown in FIG.5, taken along line B–B′.

FIG. 7 is a schematic plan view showing an active matrix substrate thatconstitutes a major part of an x-ray sensor of still another embodimentin accordance with the present invention.

FIG. 8 is a cross-sectional view showing the x-ray sensor shown in FIG.7, taken along line D–D′.

FIG. 9 is a schematic plan view showing an arrangement of a conventionalactive matrix substrate.

FIG. 10 is a cross-sectional view showing the conventional active matrixsubstrate shown in FIG. 9, taken along line F–F′.

FIG. 11 is a cross-sectional view showing the conventional active matrixsubstrate shown in FIG. 9, taken along line G–G′.

FIG. 12( a) through FIG. 12( h) are cross-sectional views showingmanufacturing steps of the conventional active matrix substrate shown inFIG. 9, taken along line F–F′.

FIG. 13( a) through FIG. 13( h) are cross-sectional views showingmanufacturing steps of the conventional active matrix substrate shown inFIG. 9, taken along line G–G′.

FIG. 14 is a schematic plan view showing an arrangement of an activematrix substrate for use in a conventional x-ray sensor.

FIG. 15 is a cross-sectional view showing the conventional active matrixsubstrate shown in FIG. 14, taken along line H–H′.

FIG. 16 is a schematic plan view showing an arrangement of an activematrix substrate of another embodiment in accordance with the presentinvention.

FIG. 17 is a cross-sectional view showing an active matrix substrateshown in FIG. 16, taken along line I–I′.

FIG. 18( a) through FIG. 18( g) are cross-sectional views showingmanufacturing steps of the active matrix substrate shown in FIG. 16,taken along line I–I′.

FIG. 19 is a schematic plan view showing an arrangement of an activematrix substrate of another embodiment in accordance with the presentinvention.

FIG. 20 is a cross-sectional view showing the active matrix substrateshown in FIG. 19, taken along line J–J′.

FIG. 21 is a schematic cross-sectional view showing an arrangement of anactive matrix substrate of another embodiment in accordance with thepresent invention.

FIG. 22 is a schematic plan view showing a variety of the active matrixsubstrate shown in FIG. 21.

FIG. 23 is a cross-sectional view showing an active matrix substrateshown in FIG. 22, taken along line K–K′.

FIG. 24 is a schematic plan view showing an arrangement of an activematrix substrate of another embodiment in accordance with the presentinvention.

FIG. 25 is a cross-sectional view showing an active matrix substrateshown in FIG. 24, taken along line L–L′.

FIG. 26 is a schematic plan view showing an arrangement of an activematrix substrate of another embodiment in accordance with the presentinvention.

FIG. 27 is a cross-sectional view showing the active matrix substrateshown in FIG. 26, taken along line M–M′.

FIG. 28 is a schematic plan view showing a major part of a variety ofthe active matrix substrate shown in FIG. 26, which is modified inneighborhoods of contact holes.

FIG. 29 is a cross-sectional view showing the active matrix substrateshown in FIG. 28, taken along line N–N′.

FIG. 30 is a schematic plan view showing an arrangement of an activematrix substrate of a further embodiment in accordance with the presentinvention.

FIG. 31 is a cross-sectional view showing the active matrix substrateshown in FIG. 30, taken along line O–O′.

DESCRIPTION OF THE EMBODIMENTS Embodiment 1

Referring to FIG. 1 through FIG. 3, the following description willdiscuss an embodiment in accordance with the present invention. Themanufacturing process of an active matrix substrate shown in FIG. 12( a)through FIG. 12( h) and FIG. 13( a) through FIG. 13( h) is applicable tothe active matrix substrate of the present embodiment, and this is oneof features of the active matrix substrate of the present embodiment.The following description is made based on these drawings and will focuson differences of the present embodiment from what is illustrated inthem. Conventional materials and manufacturing method are applicable tothe layers constituting the active matrix substrate of the presentembodiment; therefore, description thereof in detail is omitted.

As shown in FIG. 1 and FIG. 2, the active matrix substrate of thepresent embodiment includes pixels (pixel area) each encircled by signallines 11 and scanning lines 12 that are provided in a matrix, and eachpixel has a TFT 13 as a switching element near the point where thesignal line 11 crosses the scanning line 12.

A pixel capacitor wire (storage capacitor common wire) 14, disposedparallel to the signal lines 11, is a pixel capacitor common wire forconnecting together a plurality of pixel capacitors (storage capacitors)14 a provided to those pixels that are in a row parallel to the signallines 11. For example, the pixel capacitor wire 14 is connected to acommon electrode (not shown) of an opposite substrate if the activematrix substrate is used in a liquid crystal display device. Through acontact hole 15, the pixel capacitor wire 14 opposes a pixel electrode16 across a protection film (insulation film) 27 so as to form the pixelcapacitor 14 a. That is, the pixel capacitor wire 14 functions not onlyas a common wire, but also as one of two electrodes (pixel capacitorelectrode) constituting the pixel capacitor 14 a.

Further, as will be mentioned below in the description aboutmanufacturing steps, the pixel capacitor wire 14, constituted by a metalwire 26 c and a transparent electrode 25 c, is patterned concurrentlywith the formation of metal wire 26 a and a transparent electrode 25 aconstituting the signal line 11. That is, the metal wire 26 cconstituting the pixel capacitor wire 14 and the metal wire 26 aconstituting the signal line 11 are fabricated from a single layer,while the transparent electrode 25 c constituting the pixel capacitorwire 14 and the transparent electrode 25 a constituting the signal line11 are fabricated from another single layer.

Subsequently, referring to FIG. 3( a) through FIG. 3( h), the followingdescription will discuss manufacturing steps for an active matrixsubstrate of the present embodiment specifically.

As shown in FIG. 3( a), a metal film is deposited on an insulatingtransparent substrate 20 made of glass, for example, and subsequently,subjected to photolithography and dry or wet etching so as to form agate electrode 21 constituting a TFT 13 and a scanning line 12 (see FIG.1). In the manufacture of a conventional active matrix substrate(hereinafter, will be referred to as a conventional substrate), thepixel capacitor wire 105 is fabricated from a metal film at the sametime (see FIG. 12( a) and FIG. 13( a)); however, in the presentembodiment, the pixel capacitor wire 105 is not fabricated at this stageyet.

Next, a gate insulation film 22, a semiconductor layer (amorphoussilicon layer) 23, and an n⁺-Si layer (n⁺-amorphous silicon layer) 24are successively deposited and patterned as shown in FIG. 3( b). Then⁺-Si layer 24 will be later fabricated into a source electrode 24 a anda drain electrode 24 b constituting the TFT 13. The deposition andpatterning methods for these layers, as well as the pattern into whichthe layers are fabricated, are identical to those for the conventionalsubstrate.

Specifically, among the deposited films (layers), the semiconductorlayer 23 and the n⁺-Si layer 24 can be concurrently patterned into theshape that the semiconductor layer 23 should be etched. The gap of then⁺-Si layer 24, which will serve as a channel section of the TFT 13, isyet to be formed. Next, the gate insulation film 22 is patterned. Thepatterning step is, however, for the purpose of providing an externalcontact section to the scanning line 12 (see FIG. 1) near a terminal, aswell as a contact section required to supply signals to the pixelcapacitor wire 14 (see FIG. 1 and FIG. 2), for example, a contactsection with a common electrode of the opposite substrate, and is notshown in FIG. 3.

Next, a transparent electrode layer (electrode layer) 25 and a metallayer (corresponding to an electrode layer; the layer is shown in FIG.3( c) only in its patterned form) are deposited successively.Thereafter, the metal layer is patterned so as to form the metal wires26 a, 26 b, and 26 c as shown in FIG. 3( c). Subsequently, thetransparent electrode layer 25 is patterned so as to form transparentelectrodes 25 a, 25 b, and 25 c as shown in FIG. 3( d). The transparentelectrode 25 a and the metal wire 26 a correspond to the signal line 11,the transparent electrode 25 b and the metal wire 26 b correspond to aconnection electrode for establishing connection between the TFT 13 andthe pixel electrode 16 via a later-detailed contact hole 18, and thetransparent electrode 25 c and the metal wire 26 c correspond to thepixel capacitor wire 14.

The wires and the patterns have a double layer structure as in theforegoing, for the purpose of allowing for a broken wire caused by dustaccumulated during deposition of a layer and preventing the transparentelectrode layer 25 from being damaged during the patterning of theoverlying metal layer. The wires and the patterns may have a singlelayer structure in some cases. When the wires and the patterns have asingle layer structure, the materials that compose them are limited inno manner. Also, in some cases, the transparent electrode layer 25 maybe disposed on the metal layer. In the present embodiment, the pixelcapacitor wire 14, since having a double layer structure, has a reducedresistance in comparison to a pixel capacitor wire structured from asingle layer constituted by a transparent electrode film alone.

Note further that the contact section for connecting the TFT 13 to thepixel electrode 16 is fabricated from the transparent electrode 25 b asin the foregoing, because a contact section fabricated from atransparent electrode layer is less damaged in the step (detailed later)of forming the contact hole 18 and provided with better contactproperties than a contact section fabricated from a metal layer.

Subsequently, as shown in FIG. 3( e), in a transistor section that willlater serve as a TFT 13, the n⁺-Si layer 24 is etched using the metalwires 26 a and 26 b and the transparent electrodes 25 a and 25 b as amask to form a channel for the TFT 13. Next, as shown in FIG. 3( f), aprotection film 27 for protecting the exposed semiconductor layer 23 isdeposited and partly removed through etching in a contact section wherethe protection film 27 is connected to the pixel electrode 16.

The structure in which, as in the TFT 13, a source electrode 24 a and adrain electrode 24 b are disposed on a gate electrode 21 with asemiconductor layer 23 being interposed in between is called an invertedstagger structure or a bottom gate structure.

Further, as shown in FIG. 3( g), the interlayer insulation film 28 isdeposited and patterned in the contact sections (corresponding to thecontact holes 15 and 18). In the manufacture of a conventionalsubstrate, nothing more than a contact hole 116 for connecting the TFT104 to the pixel electrode 103 is formed in the contact section in theinterlayer insulation film 115 as shown in FIG. 12( g); however, in thepresent embodiment, a contact hole 15 is additionally formed that willserve as an area (detailed later) where the pixel capacitor 14 a isformed.

Subsequently, as shown in FIG. 3( h), a transparent electrode layer thatwill serve as the pixel electrode 16 is deposited on the interlayerinsulation film 28 and patterned to complete the manufacture of theactive matrix substrate of the present embodiment. The pixel electrode16 is connected to the drain electrode 24 b of the TFT 13 via thecontact hole 18 formed through the protection film 27 and the interlayerinsulation film 28.

In the contact hole 15 formed through the interlayer insulation film 28,the pixel capacitor wire 14 is disposed opposing the pixel electrode 16across the protection film 27. The metal wire 26 c constituting thepixel capacitor wire 14, the pixel electrode 16, and the protection film27 constitute a storage capacitor which serves as the pixel capacitor 14a for a pixel.

The dimensions of the pixel capacitor are determined by the dimensionsof the contact hole 15 provided in the interlayer insulation film 28(i.e., the area of the pixel capacitor 14 a where the pixel electrode 16is in contact with the protection film 27). The method of patterning theinterlayer insulation film 28 varies depending on the material of theinsulation film 28 and other factors. Generally, the interlayerinsulation film 28 is patterned through (a) etching if made of apolyimide or similar resin, and (b) photolithography if made of anacrylic or similar resin. In either of the methods, precision andaccuracy in patterning are sufficiently high, and the value of the pixelcapacitor is readily and precisely controllable.

In the active matrix substrate structured as in the foregoing, theinterlayer insulation film 28 is interposed between the pixel electrode16 and the signal and scanning lines 11 and 12, permitting the pixelelectrode 16 to overlap the signal lines 11 and the scanning lines 12.This structure allows improvements on the aperture ratio and enables theshielding of the electric field generated by the signal line 11 toprevent insufficient alignment from occurring to the liquid crystal.

Besides, the protection film 27 and the gate insulation film 22 may besubstantially identical in thickness and material. No particular changesare needed in the step of forming the protection film 27 as long as theformation of the pixel capacitor 14 a is concerned.

Conventionally, no conductive film (specifically, pixel electrode) isformed on electrode lines (signal lines, scanning lines, pixel capacitorwires, etc.) with a protection film being interposed in between;therefore, no attention has been paid to cracks of the protection filmthat develop in edge portions of the electrodes. With a priority beinggiven to the tact time, the electrode line in many cases has a steeptaper, and leak is likely to develop if the electrode line has across-section where the overlying, conductive film overlaps the edge ofthe electrode line. By contrast, in the present embodiment, as shown inFIG. 2, it is only in the contact hole 15 that the pixel electrode 16 isin contact with the electrode line with the protection film 27interposed in between; therefore, leak is no likely to develop in thecracks of the edge portion. Further, in the taper portion of the contacthole 15, the alignment of liquid crystal molecules are likely to bedisturbed by changes in thickness of the liquid crystal layer, andresult in leaks of light; however, the leaking light is blocked by theunderlying, pixel capacitor wire 14 (more precisely, the metal wire 26c), and does not interrupt a good display.

As discussed in the foregoing, an active matrix substrate that includespixel capacitor wires 14 disposed parallel to signal lines 11 can berealized by the completely identical process as the conventional stepsof manufacturing substrates only with minor changes in the pattern. Inother words, an active matrix substrate can be manufactured withcapabilities of preventing occurrence of noise and signal delays withoutan increase in the number of steps (eventually without an increase inthe manufacturing costs of the active matrix substrate). Further, themanufacturing line for conventional liquid crystal display devices canbe utilized without a change in the manufacturing process; therefore,active matrix substrates for use in high-performance liquid crystaldisplay devices or sensors can be manufactured. No investment isnecessary for a new infrastructure, and the productivity of the line isno likely to decrease.

In an active matrix substrate structured as in the foregoing, aspreviously mentioned, the pixel capacitor wire 14 crosses the scanninglines 12 alone and therefore has a greatly reduced time constant; thenoise and delays in signal transmission can be reduced by great amounts.Therefore, the active matrix substrate in accordance with the presentinvention, if applied to an image sensor, greatly improves the S/N ratioof the image sensor.

That is, if the pixel capacitor wire 14 is disposed parallel to thesignal lines 11, only one pixel that is located at a point where thepixel capacitor wire 14 crosses the selected scanning line 12 isactivated and connected by means of electric capacity to a single pixelcapacitor wire 14. As a result, at an instant when a certain scanningline 12 is selected, the electric potential of the pixel capacitor wire14 is only affected by a change in electric potential of that singlepixel, and therefore oscillates or shifts by an extremely small amount.

Further, since the pixel capacitor wire 14 is connected by means ofelectric capacity to non-selected scanning lines 12, etc., the electriccharges of the selected pixel move through redistribution to theelectrostatic capacitors constituted by the non-selected scanning liens12 and the pixel capacitor wire 14. The phenomenon further reduces theoscillation of the electric potential of the pixel capacitor wire 14 andallows the pixel capacitor wire 14 to quickly return to normal voltageconditions.

Since the pixel capacitor wire 14 does not cross the signal lines 11,the electrostatic capacitors constituted by the non-selected scanninglines 12 and the pixel capacitor wire 14 are not affected by the signallines 11. Consequently, the electrostatic capacitors constituted by thenon-selected scanning lines 12 and the pixel capacitor wire 14 do notnegatively affect the electric potential of the pixel where a signal isbeing read or written.

As in the foregoing, unlike conventional technology, the electricpotential of the pixel capacitor wire 14 can be stabilized with littleneed to form the pixel capacitor wire 14 with a low resistance as awhole or to restrain the impedance of the pixel capacitor wire 14 withrespect to an input terminal of the pixel capacitor wire 14.

Further, a signal of a constant amplitude and 180° out of phase with thesignal supplied to the signal lines 11 may be supplied to oppositeelectrodes (not shown) and the pixel capacitor wire 14 in order toreduce the amplitude of the signal supplied to the signal lines 11. Whenthis is the case, so-called floating gate drive is carried out whereby asignal having the same amplitude and phase as the signal supplied to thesignal lines 11 is superimposed on the off electric potential of thescanning lines 12; therefore, the voltage difference between the pixelcapacitor wires 14 and the scanning lines 12 is always constant. Inother words, no capacitor components other than a stray capacitycontribute to an increase in the time constant of the pixel capacitorwire 14, and it is safe to say that there are substantially no actualdelays occurring in signal transmission. Besides, since the TFTs 13(only one of them is shown) of those pixels that are connected to acommon pixel capacitor wire 14 are not turned on simultaneously asmentioned previously; therefore, crosstalk and other problems are nolikely to develop.

Meanwhile, in the conventional active matrix substrate shown in FIG. 14and FIG. 15, the pixel capacitor wire 205 is disposed parallel to thesignal line 201. However, an additional step is necessary to form apixel capacitor wire 205 b; namely, the steps of (a) providing atransparent electrode film that will serve as the pixel capacitorelectrodes 205, and (b) depositing, subjecting to photolithography, andetching the gate insulation film 210 b to provide a contact sectionbetween the pixel capacitor wire 205 b and the pixel capacitor electrode205. Further, a high level of precision is required in the patterning ofthe gate insulation film 210 b. This is achievable through the use ofcostly photomasks and precise controls of conditions in exposure tolight and etching, but results in increased costs.

In the present embodiment, the pixel electrode 16 is fabricated from atransparent electrode layer. However, there are alternatives. Forexample, when the active matrix substrate is to constitute a liquidcrystal display device of a reflective type, the pixel electrode 16 maybe fabricated from a metal film.

Further, when there are few requirements on the aperture ratio and thearea occupied by the pixel electrode 16, provided that the pixelelectrode is further reduced in its circumference to eliminate theoverlapping of the pixel electrode 16 with the signal line 11 and thescanning line 12, the problem of parasitic capacity is solved thatdevelop between the signal line 11 and the pixel electrode 16 andbetween the scanning line 12 and the pixel electrode 16.

Further, if the parasitic capacity does not pose a problem, there is noneed to provide the interlayer insulation film 28, and the steps ofdepositing and patterning the interlayer insulation film 28 can beomitted.

Embodiment 2

Referring to FIG. 4, the following description will discuss anotherembodiment in accordance with the present invention. Here, forconvenience, members of the present embodiment that have the samearrangement and function as members of the first embodiment, and thatare mentioned in the first embodiment are indicated by the samereference numerals and description thereof is omitted.

The active matrix substrate of the present embodiment differs from theactive matrix substrate of the first embodiment in the arrangement ofpixel capacitor wires. Specifically, in the present embodiment, as shownin FIG. 4, the pixel capacitor wire (storage capacitor common wire) thattakes a dual role as a storage capacitor electrode has a single layerstructure constituted by a transparent electrode (transparent electrodefilm) 25 c alone. In other words, the patterning of the pixel capacitorwire of the present embodiment is carried out concurrently with theformation of the transparent electrode 25 a constituting the signal line11. With this arrangement, the pixel capacitor wire has a single layerstructure constituted by the transparent electrode 25 c alone;therefore, the aperture ratio of the pixel can be improved further overthe arrangement of the first embodiment. Note that FIG. 4 corresponds tothe cross-sectional view taken along line A–A″ shown in FIG. 1 whichillustrates the first embodiment.

The manufacturing process of an active matrix substrate of the presentembodiment is identical to the manufacturing process explained in thefirst embodiment (see FIG. 3( a) through FIG. 3( h)), except that themetal wire 26 c is further removed in the patterning of the metal layerdeposited on the transparent electrode layer (electrode layer) 25, andtherefore requires no additional steps.

Further, since the pixel capacitor wire is not a factor reducing theaperture ratio of the pixel, the value of the pixel capacitor (that is,the area of the transparent electrode 25 c opposing the pixel electrode16 across the protection film (insulation film) 27) can be increased asnecessary. For example, crosstalk, when likely to occur due to theparasitic capacity between the signal line 11 and the pixel electrode16, can be readily solved.

Recently, in some cases, the signal line 11 per se has a single layerstructure constituted by the transparent electrode 25 a alone to reducecosts. In such a case also, the pixel capacitor wire can be fabricatedfrom the transparent electrode 25 c in the same manner as in theforegoing.

In some cases, the fabrication of the pixel capacitor wire from thetransparent electrode 25 c causes a relatively large resistance comparedto a metal wire. The phenomenon can be prevented from resulting introuble by adjusting, as necessary, the value of the pixel capacity ofthe transparent electrode 25 c which doubles as a pixel capacitorelectrode (storage capacitor electrode).

Embodiment 3

Chiefly referring to FIG. 5 and FIG. 6, the following description willdiscuss a further embodiment in accordance with the present invention.Here, for convenience, members of the present embodiment that have thesame arrangement and function as members of the previous embodiments,and that are mentioned in the previous embodiments are indicated by thesame reference numerals and description thereof is omitted.

As shown in FIG. 5 and FIG. 6, the active matrix substrate for use in aflat-panel-type x-ray sensor of the present embodiment (hereinafter willbe simply referred to as an x-ray sensor) includes pixels each encircledby signal lines 11 and scanning lines 12 that are provided in a matrix,and each pixel has a TFT 13 as a switching element near the point wherethe signal line 11 crosses the scanning line 12. Each pixel is providedwith a transparent electrode (transparent electrode film) 25 d as apixel capacitor wire (storage capacitor common wire), a pixel electrode16, and a contact hole 15 formed through an interlayer insulation film28. In the contact hole 15 a, a transparent electrode 25 d and a pixelelectrode 16 are disposed opposing each other across a protection film(insulation film) 27, so as to form a pixel capacitor (storagecapacitor) 30 a. In other words, the transparent electrode 25 d takesdual roles as a pixel capacitor wire and a pixel capacitor electrode(storage capacitor electrode) as in the previous embodiments.

The transparent electrode 25 d is fabricated concurrently with thetransparent electrode 25 a that constitutes an underlayer of the signalline 11 through patterning the transparent electrode layer (electrodelayer) 25 shown in FIG. 3( c) as in the second embodiment.

The cross-sectional structure taken along line C–C′ in FIG. 5 isidentical to that taken along line A–A′ in FIG. 1, thereby not beingshown in drawings. Further, the active matrix substrate includesdeposited layers that has an identical structure (i.e., identicalsequence in deposition of the layers) to those in the first and secondembodiments, and changes are made only to the patterns of some layers;description about manufacturing steps are thereby omitted.

The structure of the x-ray sensor further includes a conversion layer(conversion section) 31 and a common electrode layer (bias voltageapplication means) 32 sequentially deposited on the active matrixsubstrate (see FIG. 6). The conversion layer 31 is not limited in anyparticular manner, provided that it generates electron-positive holepairs upon reception of energy, such as x-rays: specific examplesinclude layers formed by deposition of a-Se, Cd.Ta, and other suchsemiconductors in a suitable thickness. Suitably thin films of thesematerials may be deposited to form a pin connection and shot keyconnection as a precautionary measure to curb current leaks betweenpixels.

Next, operations of the x-ray sensor will be briefly explained. As anx-ray enters the x-ray sensor through the top (i.e., through the commonelectrode layer 32), the energy of the x-ray causes the conversion layer31 to generate electron-positive hole pairs. Since the common electrodelayer 32 is provided with a constant bias voltage and the transparentelectrode 25 d is maintained at a constant electric potential, theelectron-positive hole pairs move as if they were attracted by the biasvoltage and build up electric charges in the pixel capacitor 30 a. Theelectric charges stored in the pixel capacitor 30 a are read through thesignal line 11 via the TFT 13 selected by means of the scanning line 12.

To improve the efficiency in collecting the electric charges convertedfrom an x-ray and to prevent an abnormally increased pixel electricpotential from causing leaks of electric charges from the TFT 13 orcausing the destruction of the TFT 13 per se, the active matrixsubstrate of the present embodiment has a greatly increased pixelcapacity (more specifically, a greatly increased area where thetransparent electrode 25 d opposes the pixel electrode 16).

Incidentally, the aperture ratio of an x-ray sensor is in many cases notnecessarily as large as that of a liquid crystal display device of atransparent type; therefore, the materials composing the pixel capacitorwire and the pixel capacitor electrode are not limited in any particularmanner. Even a metal wire is applicable.

However, due to the nature of the conversion layer 31, electric chargesmay still remain in the conversion layer 31 in small quantities afterelectric charges stored in the pixel capacitor 30 a are read. Theseremaining electric charges possibly degrade signal precision and causepolarization, rendering the conversion layer 31 per se less reliable. Toprevent this from happening, for example, a method is applicable wherebylight is projected to the entirety of the x-ray sensor to refresh theconversion layer 31 (the conversion layer discharges the remainingelectric charges) at fixed intervals (for example, at every intervalbetween read-out frames). When this is the case, light and x-ray arepreferably projected from different sides; therefore, smaller lightblocking area is preferred between the transparent substrate 20 and theconversion layer 31. In the present embodiment, the light blocking areabetween the transparent substrate 20 and the conversion layer 31 can bemade extremely small, since the pixel capacitor wire (doubles as a pixelcapacitor electrode) is fabricated from the transparent electrode 25 d.

Embodiment 4

Chiefly referring to FIG. 7 and FIG. 8, the following description willdiscuss a further embodiment in accordance with the present invention.Here, for convenience, members of the present embodiment that have thesame arrangement and function as members of the previous embodiments,and that are mentioned in the previous embodiments are indicated by thesame reference numerals and description thereof is omitted.

The x-ray sensor of the present embodiment differs from the x-ray sensorof the third embodiment primarily in the arrangement of the pixelcapacitor wires and the pixel capacitors. Specifically, in the presentembodiment, a metal wire 26 d that serves as a pixel capacitor wire(storage capacitor common wire) is formed on a transparent electrode(transparent electrode film) 25 d that serves as a pixel capacitorelectrode (storage capacitor electrode). A pixel capacitor wire and apixel capacitor electrode are fabricated from the same layer as is thesignal line 11. Specifically, the metal wire 26 a serving as the upperlayer of the signal line 11 and the metal wire 26 d serving as the pixelcapacitor wire are fabricated from a single metal layer throughpatterning thereof, while the transparent electrode 25 a as the lowerlayer of the signal line 11 and the transparent electrode 25 d servingas the pixel capacitor electrode are fabricated from a singletransparent electrode layer (electrode layer) 25 through patterningthereof (see FIG. 3( c)).

In the arrangement of the present embodiment, the fabrication of atleast the transparent electrode 25 a serving as the lower layer of thesignal line 11 and the transparent electrode 25 d serving as the pixelcapacitor electrode from the same layer suffices to give the presentinvention an advantage over conventional technology; the formation ofthe metal wire 26 a serving as the upper layer of the signal line 11 isnot essential. In other words, as previously mentioned, the signal line11 may have a single layer structure.

Besides, as mentioned in the first embodiment, leak is likely to occurif the pixel electrode 16 has a cross-section where it overlaps the edgeof the electrode line; therefore, the interlayer insulation film 28 isprovided with two contact holes 15 b where pixel capacitors (storagecapacitors) 30 b are formed so as to skirt the edges of the metal wire26 d. The pixel capacitors 30 b sit flat because of the arrangement ofthe pixel electrode 16, the protection film (insulation film) 27, andthe transparent electrode 25 d.

The cross-sectional structure taken along line E–E′ in FIG. 7 isidentical to that taken along line A–A′ in FIG. 1, thereby not beingshown in drawings. Further, the active matrix substrate includesdeposited layers that have an identical structure to those in the firstand second embodiments, and changes are made only to the patterns ofsome layers; description about manufacturing steps are thereby omitted.

In the x-ray sensor of the present embodiment, the pixel capacitor wire,since being made of metal (metal wire 26 d), has a reduced resistance incomparison to a pixel capacitor wire structured from a transparentelectrode film. Besides, the pixel capacitor electrode is fabricatedfrom the transparent electrode 25 d; therefore, light and an x-ray canbe projected from opposing sides so as to readily refresh the conversionlayer 31.

The active matrix substrate for use in x-ray sensors of the third andfourth embodiments can be readily manufactured at low costs without newinvestment in manufacturing tools and facilities, because the samemanufacturing process can be applied as that for conventional liquidcrystal display devices only by adjusting the dimensions of the pixelcapacitor and the time constant of the active element (switchingelement) so as to be optimal when used in a sensor.

Further, the signal line 11 does not cross the pixel capacitor wire;therefore, the load capacity on the signal line 11 can be greatlydecreased, and noise and delays in signal transmission can be greatlyrestrained, and the impedance of the pixel capacitor wire can also bedecreased. Moreover, when a certain line is selected by means of thescanning line 12, the noise generated in the pixel capacitor wire maypropagate along the signal lines 11, but does not propagate along thescanning line 12, causing no interference with the data read through thepixels simultaneously selected.

The structure of the x-ray sensor is by no means limited to theforegoing example: an alternative example is to make use of a methodwhereby an x-ray is converted to visual light and then read using aphotodiode. The method can be effected in various fashions: for example,(A) electric charges are stored in a pixel capacitor and then dischargedaccording to a signal from the scanning lines, and the differencebetween the discharged electric charges and the initial electric chargesis read, or (B) the current flowing through the photodiode is stored inthe pixel capacitor and read. Despite that the layer depositionstructure on the active matrix substrate is different in these methodsand in the aforementioned method of converting x-ray energy directlyinto electric charges, an identical active matrix substrate can be usedin all the methods, because a common structure is adoptable below pixelelectrodes.

Further, if a light conductive film is used in place of theradiation-to-electric charges conversion film as the conversion layer31, the image sensor will respond to magnetoelectric radiation includingvisual light and infrared light instead of x-rays.

Embodiment 5

Referring to FIG. 16 through FIG. 19, the following description willdiscuss a further embodiment in accordance with the present invention.The manufacturing process of an active matrix substrate shown in FIG.12( a) through FIG. 12( h) and FIG. 13( a) through FIG. 13( h) isapplicable to the active matrix substrate of the present embodiment, andthis is one of features of the active matrix substrate of the presentembodiment. The following description is made based on these drawingsand will focus on differences of the present embodiment from what isillustrated in them. Conventional materials and manufacturing method areapplicable to the layers constituting the active matrix substrate of thepresent embodiment; therefore, description thereof in detail is omitted.

As shown in FIG. 16 and FIG. 17, an active matrix substrate of thepresent embodiment includes pixels (pixel area) each encircled by signallines 11 and scanning lines 12 that are provided in a matrix, and eachpixel has a TFT 13 as a switching element near the point where thesignal line 11 crosses the scanning line 12.

A pixel capacitor wire (storage capacitor common wire) 14, disposedparallel to the signal lines 11, is a pixel capacitor common wire forconnecting together a plurality of pixel capacitors (storage capacitors,supplementary capacitors) 14 a provided to those pixels that are in arow parallel to the signal lines 11. For example, the pixel capacitorwire 14 is connected to common electrodes (not shown) of an oppositesubstrate if the active matrix substrate is used in a liquid crystaldisplay device. In a contact hole 40, the pixel capacitor wire 14 iselectrically connected to a pixel capacitor electrode 41 which isdisposed opposing a pixel electrode 43 across a gate insulation film 42as shown in FIG. 17, so that the pixel capacitor electrode 41 and thepixel electrode 43 constitute a pixel capacitor 14 a.

Further, as will be mentioned below in the description aboutmanufacturing steps, the pixel capacitor electrode 41 and the scanningline 12 are concurrently fabricated from the same layer throughpatterning thereof.

Now, referring to FIG. 18( a) through FIG. 18( g), the followingdescription will discuss manufacturing steps of the active matrixsubstrate of the present embodiment specifically.

As shown in FIG. 18( a), a metal film 51 (corresponding to an electrodelayer) made of Ta, for example, is deposited on an insulatingtransparent substrate 50 made of glass, for example, and subsequently,subjected to photolithography and dry or wet etching so as toconcurrently form the pixel capacitor electrode 41 (FIG. 18( b)) as wellas a gate electrode 21 constituting a TFT 13 and a scanning line 12 (seeFIG. 16). In this manner, the pixel capacitor electrode 41 and thescanning line 12 including the gate electrode 21 are concurrentlyfabricated from the same layer, i.e., the metal film 51, throughpatterning thereof. The pixel capacitor electrode 41 is provided to aportion that will serve as an underlying layer to the pixel electrode43.

Subsequently, the gate electrode 21 and the scanning line 12 areanodized so as to form an anodization film 44 on the gate electrode 21and the scanning line 12 (FIG. 18( c)), while the gate electrode 21 andthe scanning line 12 are electrically coupled to the anode of a powersource. No anodization film is formed on the pixel capacitor electrode41 which is fabricated from the same layer as are the gate electrode 21and the scanning line 12. This is because the pixel capacitor electrodes41, formed like mutually separated islands so that each of them isprovided to a different pixel from the others, are electricallyseparated from external circuits and do not change while the scanninglines 12 are being anodized through electrical connection to an anode ofa power supply.

Next, a gate insulation film 42, a semiconductor layer 52, and an n⁺-Silayer 53 are successively deposited and patterned as shown in FIG. 18(c). The n⁺-Si layer 53 will be later fabricated into a source electrode53 a and a drain electrode 53 b constituting the TFT 13. The depositionand patterning methods for these layers, as well as the pattern intowhich the layers are fabricated, are identical to those for theconventional substrate.

Specifically, among the deposited films (layers), the semiconductorlayer 52 and the n⁺-Si layer 53 can be concurrently patterned into theshape that the semiconductor layer 52 should be etched. The gap of then⁺-Si layer 53, which will serve as a channel section of the TFT 13, isyet to be formed. Next, the gate insulation film 42 is patterned. Thepatterning step is, however, for the purpose of providing an externalcontact section to the scanning lines 12 (see FIG. 16) near theterminals, as well as a contact section required to supply signals tothe pixel capacitor wire 14 (see FIG. 16 and FIG. 17), for example, acontact section with a common electrode of the opposite substrate.Further, the patterning step is for forming a portion that will serve asa contact hole 40 for electrically connecting the pixel capacitor wire14 to the pixel capacitor electrode 41 when the pixel capacitor wire 14is disposed.

Next, a transparent conductive layer 54 (corresponding to a conductivelayer), which will be fabricated into the signal line 11 and the pixelelectrode 43, is deposited immediately followed by the deposition of ametal layer 55 (shown in FIG. 18( d) only in its patterned form).Thereafter, the metal layer 55 is patterned first as shown in FIG. 18(d). Subsequently to the patterning of the metal layer 55, thetransparent conductive layer 54 is patterned so as to form a transparentelectrode 54 a, a pixel electrode 43, and a pixel capacitor wire 14 asshown in FIG. 18( e). That is, in the conventional step, only the signalline and the source and drain electrode for the TFT are formed. Bycontrast, in the present invention, concurrently with the deposition ofthe transparent conductive layer 54, the major portion of the signalline 11 and the major portion of the pixel capacitor wire 14 are formedparallel so that the major portion of the pixel capacitor wire 14 isparallel to the signal line

Hence, the pixel electrode 43 and the pixel capacitor electrode 41 thathas been formed of Ta in advance concurrently with the scanning line 12constitute the pixel capacitor 14 a across the gate insulation film 42.

The transparent electrode 54 a and the metal layer 55 deposited thereoncorrespond to the signal line 11. Besides, the transparent conductivelayer 54 is typically made of ITO (Indium Tin Oxide).

Subsequently to FIG. 18( e), as shown in FIG. 18( f), in a transistorsection that will later serve as a TFT 13, the n⁺-Si layer 53 is etchedusing the transparent conductive layer 54 and the metal layer 55patterned as shown in FIG. 18( e) as a mask to form a channel for theTFT 13.

Next, as shown in FIG. 18( g), the protection film 45 for protecting theexposed semiconductor layer 52 is deposited and partly removed throughetching where the protection film 45 overlies the pixel electrode 43, soas to form an aperture section 46 as shown in FIG. 16.

On the thus-completed active matrix section, a conversion layer made ofselenium and the like is deposited, and then, electrodes are provided tothe conversion layer to receive a bias voltage to complete manufactureof an image sensor.

As in the foregoing, the scanning line 12 and the gate electrode 21 ofthe TFT 13 have a double insulating layer structure constituted by thegate insulation film 42 and the anodization film 44. This is to preventdefective lines and other such serious display defects from occurringwhen the gate insulation film 42 develops cracks or perforations throughwhich electricity leaks.

By contrast, in the pixel capacitor 14 a, such leaks, if ever happen,are confined in tiny local areas; therefore, insulation is of lessimportance in the pixel capacitor 14 a than in the scanning line 12 andthe TFT 13. Rather, since the dielectric layer sandwiched between thepixel capacitor electrode 41 and the pixel electrode 43 in the pixelcapacitor 14 a has a single layer structure constituted by the gateinsulation film 42, the dielectric layer has an increased permitivityand hence an increased electrostatic capacity per unit area. Thedielectric layer therefore offers a relatively large supplementarycapacity for the small area that it occupies.

Typically, the image sensor is specified to have a large supplementarycapacity so as to prevent the electric charges generated in theconversion layer from undesirably increasing the electric potential ofthe pixel. Therefore, the image sensor becomes much more useful when itis structured to boast a larger electrostatic capacity per unit area.

Incidentally, the signal line 11 has a double layer structure asdiscussed in the foregoing for the purpose of allowing for a broken wirecaused by dust accumulated during deposition of a layer and preventingthe underlying layer from being damaged during the patterning of theoverlying metal layer 55. The provision of the double layer signal line11 is a conventional scheme to solve these problems.

Besides, possibly, the transparent conductive layer 54 may be depositedon the metal layer 55 or vice versa. In the present invention also, anyof the two layers may be deposited on the other.

Further, in the present embodiment, the pixel capacitor wire 14 does notneed to have a reduced resistance; therefore, no metal layer 55 isdeposited on the transparent conductive layer 54, rendering thetransparent conductive layer 54 as a single layer. However, if the gateinsulation film 42 in the contact hole 40 has a sharp edge in itscross-section, the transparent conductive layer 54 is often damaged bythe sharp edge. Therefore, to give more credibility to the deposition ofthe transparent conductive layer 54 in the contact hole 40, thetransparent conductive layer 54, combined with the metal layer 55,preferably constitutes a double layer structure similarly to that foundin the signal line 11.

In active matrix substrate of the present embodiment, as mentioned inthe foregoing, the pixel capacitor wire 14 only crosses with thescanning line 12, thereby greatly reducing the time constant of thepixel capacitor wire 14. Accordingly, noise and delays in signaltransmission hardly matter. Besides, as mentioned in the foregoing, theTFTs 13 belonging to those pixels that share a single pixel capacitorwire 14 are never turned on; therefore, it is no likely that the signalsread from the pixels interfere with each other and degrades accuracy inthe reading.

Further, if the pixel capacitor electrode 41 is fabricated from the samelight blocking metal film as is the scanning line 12, so as to have anextended area, its use in a liquid crystal display device of atransparent type is likely to result in reduced aperture ratios, whereasits use in an image sensor is not problematic. This is because in thelatter case, a part of the pixel electrode 43 that is in contact withthe conversion layer is regarded as contributing to the aperturesection, and a large supplementary capacity can be formed below thepixel electrode 43 from the same material as the scanning line 12without a problem.

In the pixel, no pixel electrode 43 can be disposed in close proximityof the pixel capacitor wire 14, reducing the aperture area inevitably.However, in an image sensor, electric charges generated by an x-ray andthe like are collected at the pixel electrode 43 due to a high voltageapplied to the conversion layer; therefore, the reduce aperture areadoes not seriously affect the reading of signals.

As in the foregoing, the manufacture of an image sensor in accordancewith the present invention follows the same process as the conventionalmanufacture of an active matrix substrate, with only patterns beingmodified. As a result, the number of steps can be prevented fromincreasing, and eventually, the manufacturing cost of an active matrixsubstrate can be prevented from rising.

Meanwhile, the previously-explained conventional active matrix substratefor use in a sensor where the pixel capacitor common wire 205 b isdisposed parallel to the signal line 201 as shown in FIG. 14 has thesame advantages as to noise and signal delays as those of the presentinvention. That being said, in the present invention, the pixelcapacitor electrode 41 is formed from the same material in the same stepas the scanning line 12; unlike the active matrix substrate shown inFIG. 14, there is no need to form the underlying gate insulation film210 a prior to the formation of the pixel capacitor electrode 205.

In other words, in the arrangement shown in FIG. 15, the underlying gateinsulation film 210 a is deposited, and the pixel capacitor electrode205 is deposited and patterned successively, after the formation of thescanning line 202 including the gate electrode. By contrast, by theprocess in accordance with the present invention, there is no stepcorresponding to the step of depositing the underlying gate insulationfilm 210 a, and the pixel capacitor electrode 41 and the scanning line12 are deposited and patterned concurrently. Therefore, the process inaccordance with the present invention is more flexible in reducing thenumber of steps and costs than the process of manufacturing an activematrix substrate as shown in FIG. 15.

After the gate insulation film 210 b is completely formed in the stepshown in FIG. 14, the film arrangement appears simpler than the filmarrangement in accordance with the present invention at a first sight.However, the total number of steps is inevitably larger in such aprocess that includes the step shown in FIG. 14 than in the process inaccordance with the present invention, if the following two points areconsidered: (1) In the present invention, the pixel capacitor wire 14does not necessarily have a double layer structure as mentioned in theforegoing, (2) In FIG. 14, no protection film is formed to protect thesemiconductor layer, but an inorganic protection film is preferablyinterposed between the semiconductor layer and the interlayer insulationfilm (polymer layer) that is typically formed from an organic film so asto improve on the credibility of the device.

Embodiment 6

Referring to FIG. 19 and FIG. 20, the following description will discussa further embodiment in accordance with the present invention. Here, forconvenience, members of the present embodiment that have the samearrangement and function as members of the previous embodiments, andthat are mentioned in the previous embodiments are indicated by the samereference numerals and description thereof is omitted. Besides,conventional materials and manufacturing method are applicable to thelayers constituting the active matrix substrate of the presentembodiment. Therefore, the manufacturing method of the layersconstituting the active matrix substrate of the present embodiment issimilar to those discussed earlier in reference to FIG. 3( a) throughFIG. 3( h) and FIG. 18( a) through (g), and will be discussed only inreference to those Figures; detailed step diagrams are omitted.

As shown in FIG. 19 and FIG. 20, the active matrix substrate of thepresent embodiment has features in such an arrangement that a pixelelectrode 63 and scanning lines 12 including a gate electrode 21 areconcurrently fabricated from a single layer through patterning thereofand a pixel capacitor wire 14 is provided parallel to signal lines 11 soas to pass near the center of that area where a pixel is formedencircled by the signal lines 11 and the scanning lines 12.

As shown in FIG. 20, the pixel capacitor wire 14 and the pixel electrode63 constitute the pixel capacitor 14 a, as the pixel capacitor wire 14is disposed on the pixel electrode 63 with the gate insulation film 42being interposed in between.

Now, the following description will discuss manufacturing steps of theactive matrix substrate of the present embodiment more specifically.

Similarly to the step shown in FIG. 18( a) discussed in the lastembodiment, a metal film (correspond to an electrode layer) made of, forexample, Ta is deposited on the insulating transparent substrate 50 madeof, for example, glass, and then subjected to photolithography and dryor wet etching similarly to the step shown in FIG. 18( b), so as toconcurrently form the gate electrode 21 constituting the TFT 13 and thescanning line 12 and the pixel electrode 63 in an island-like shape (seeFIG. 19 and FIG. 20). In this manner, the pixel electrode 63 and thescanning line 12 including the gate electrode 21 are concurrently formedfrom the same metal film through patterning thereof.

Subsequently, the gate electrode 21 and the scanning line 12 areanodized so as to form an anodization film 44 on the gate electrode 21and the scanning line 12, while the gate electrode 21 and the scanningline 12 are electrically coupled to the anode of a power source. Noanodization film is formed on the pixel electrode 63 which is fabricatedfrom the same layer as are the gate electrode 21 and the scanning line12. This is because the pixel electrodes 63, formed like mutuallyseparated islands so that each of them is provided to a different pixelfrom the others, are electrically separated from external circuits anddo not change while the scanning lines 12 are being anodized throughelectrical connection to an anode of a power supply.

Next, a gate insulation film 42, a semiconductor layer 52, and an n⁺-Silayer are successively deposited. The n⁺-Si layer will be laterfabricated into a source electrode 53 a and a drain electrode 53 b. Thesemiconductor layer 52 and the n⁺-Si layer are then patterned, which isimmediately followed by the patterning of the gate insulation film 42.Specifically, the gate insulation film 42 is etched so as to leave aportion thereof corresponding to the pixel capacitor wire 14 intact nearthe middle of the pixel electrode 63 and to form substantiallyrectangular aperture sections 66 flanking that portion.

Next, similarly to the steps shown in FIG. 3( c) and FIG. 3( d), thesignal line 11 constituted by the transparent electrode 54 a and themetal wire 55 a, the connection electrode 67 constituted by thetransparent electrode 54 b and the metal wire 55 b, and the pixelcapacitor wire 14 constituted by the transparent electrode 54 c and themetal wire 55 c are formed together. In other words, the transparentelectrode 54 b of the signal line 11 and the transparent electrode 54 cof the pixel capacitor wire 14 are fabricated from the same transparentconductive layer through patterning thereof, and the metal wire 55 b ofthe signal line 11 and the metal wire 55 c of the pixel capacitor wire14 are fabricated from the same metal layer (conductive layer) throughpatterning thereof.

Here, the transparent electrode 54 b and the metal wire 55 bconstituting the connection electrode 67 are extended from the positionwhere the drain electrode 53 b of the TFT 13 is formed, so as to reachthe previously formed pixel electrode 63 and become electrically coupledto the pixel electrode 63 at the aperture section 66 on the side of thedrain electrode 53 b.

Subsequently, similarly to FIG. 3( e) and FIG. 3( f), the channel of theTFT 13 and the protection film 45 are formed. The protection film 45 isformed in the same pattern as is the gate insulation film 42; therefore,the photomask used for the patterning of the gate insulation film 42 canbe used as it is, which will contribute to a reduction in themanufacturing cost of the active matrix substrate.

In the foregoing, the gate insulation film 42 is patterned after theformation of the semiconductor layer 52 and the n⁺-Si layer and beforethe deposition of the transparent conductive layer and the metal layerwhich will be concurrently fabricated into the signal line 11 and thepixel capacitor wire 14. Alternatively, the gate insulation film 42 andthe protection film 45 may be patterned concurrently after thedeposition of the protection film 45. This is possible because theprotection film 45 is made of the substantially same material as is thegate insulation film 42.

By concurrently patterning the protection film 45 and the gateinsulation film 42 in this manner, the number of steps is greatlyreduced, and large cost reductions are successfully achieved. Besides,since the formation of the aperture section 66, which will expose thepixel electrode 63, is carried out in a finishing stage, the surface ofthe pixel electrode 63 is contaminated minimally before a conversionlayer is deposited on the pixel electrode 63. The conversion layer cantherefore be formed in a stable manner.

Incidentally, in the present embodiment, to increase the pixel capacitor14 a, the pixel capacitor wire 14 formed on the pixel electrode 63 needsto expanded in width; therefore, the aperture sections 66 shouldinevitably be scaled down.

However, in a reverse situation where the pixel capacitor 14 a isallowed to be relatively small, no area needs to be set aside toaccommodate a contact hole 40 as shown in FIG. 16 discussed in the lastembodiment. Further, no spatial room needs to be interposed between thepixel electrode 43 and the pixel capacitor wire 14 and between the pixelcapacitor wire 14 and the signal line 11, whereas the room is notdisposable in the arrangement shown in FIG. 16.

Consequently, if the pixel capacitor 14 a is allowed to be relativelysmall, the aperture sections 66 are allowed to be made relatively large.The pixel capacitor 14 a is allowed to be relatively small when, forexample, the device is designed only for a high speed video recording ordesigned compatibly for both video and still picture recordings; in thelatter case, however, each still picture image is obtained bysynthesizing image data representative of two or more frames, which isoften done for noise reduction and other purposes. In these events,without specifying the pixel capacitor wire 14 to a large value, theelectric potential of the pixel can be prevented from risingexcessively, which otherwise could be a cause for leak of electriccharges or destruction of the TFT 13.

Generally, it is difficult to form a contact hole that has a lowresistance and permits establishment of good contact, because thecontact hole is physically a small dent and foreign objects includingscum are easy to pile up on the bottom of the contact hole when thecontact hole is etched out. Besides, because of the pile-up of foreignobjects, the smaller the contact hole, the greater the contactresistance per unit area. Therefore, in the last embodiment, the contacthole 40 may be a cause for trouble if it is reduced too much in size.The above is reasons why a marginal area needs to be set aside to formthe contact hole 40 in the arrangement shown in FIG. 16.

Note that in the present embodiment, the foregoing reasons are takenwell into account and the aperture section 66 is designed with a maximumaperture area; therefore, foreign objects including scum are no likelyto collect, enabling the connection electrode 67 to be electricallycoupled to the pixel electrode 63 in the aperture section 66 in asatisfactory fashion.

Besides, unlike the arrangement shown in FIG. 16, the pixel capacitorwire 14 can be disposed to pass through the center of the pixel,separate portions where electric charges are hardly storable are createdbetween adjacent pixels and in the center of the pixel by suchspecification that the gap between the pixel electrodes 63 belonging toadjacent pixels is smaller than the gap between the pixel electrodes 43shown in FIG. 16. This arrangement increases efficiency in collectingelectric charges.

In the foregoing, the present embodiment is discussed on the assumptionthat the scanning line 12 and the pixel electrode 63 are fabricated fromthe same Ta layer; however, Ta is not the only material for them. Aproper material may be selected from Al, Mo, and other materials,provided that it satisfies compatibility with the physical nature of theconversion layer and allows effective use of the conventionalmanufacturing line for the active matrix substrate.

Embodiment 7

Referring to FIG. 21 through FIG. 23, the following description willdiscuss a further embodiment in accordance with the present invention.Here, for convenience, members of the present embodiment that have thesame arrangement and function as members of the previous embodiments,and that are mentioned in the previous embodiments are indicated by thesame reference numerals and description thereof is omitted.

In the arrangement of the sixth embodiment, if the effective use of theconventional manufacturing line for the active matrix substrate takesprecedence, it may become difficult to make a right choice as to thematerial for the scanning line 12 and the pixel electrode 63 thatsatisfies compatibility with the physical nature of the conversionlayer.

Besides, the metal layer serving as the pixel electrode 63, if leftexposed, is highly likely to be oxidized at its surface, which mayinterrupt a satisfactory level of conductance with the conversion layer.Especially, when the conversion layer is made of an amorphous selenium,since the amorphous selenium is highly susceptible to heat and water, astep of cutting or a step of mounting a circuit may be performed priorto deposition of an amorphous selenium. It is essential that the surfaceconditions of the pixel electrode 63 do not degrade until the amorphousselenium is deposited thereon after the cutting or mounting step isperformed.

Accordingly, the aforementioned aperture section 66 may be covered witha transparent conductive layer as in the present embodiment shown inFIG. 21. The transparent conductive layer is preferably made of ITO,which is conventionally used for the pixel electrode in the activematrix substrate.

Further, the step of patterning transparent electrodes 54 a, 54 b, and54 c that will constitute a signal line 11, a connection electrode 67,and a pixel capacitor wire 14 respectively is applicable to the step ofcovering the aperture section 66 with a transparent conductive layerafter the patterning of the metal wires 55 a, 55 b, and 55 c that willconstitute the signal line 11, the connection electrode 67, and thepixel capacitor wire 14 respectively. Hence, the active matrix substratecan be manufactured with improved reliability and increased yields,without losing any of the advantages of the present embodiment andmodifying the manufacturing steps of the conventional active matrixsubstrate.

More specifically, when the transparent conductive layer deposited onthe pixel electrode 63 to form the transparent electrodes 54 a, 54 b,and 54 c is patterned, as shown in FIG. 21, the transparent electrode 54b and the transparent conductive film 54 d are left unremoved on theaperture sections 66 so as not to be in contact with the transparentelectrode 54 c constituting the pixel capacitor wire 14.

FIG. 22 and FIG. 23 show a modification of the arrangement shown in FIG.21. In the modification, the pixel electrode 63 is replaced by anunderlying pixel electrode 63 a (corresponding to the second pixelelectrode) that is shorter than the pixel electrode 63 shown in FIG. 21,but slightly longer than the pixel capacitor wire 14, when measuredparallel to the scanning line 12. In accordance with this, as shown inFIG. 23, a gate insulation film 42 and a transparent electrode 54 b ₁(corresponding to a first pixel electrode) or a gate insulation film 42and a transparent electrode 54 e (corresponding to first pixelelectrode) are deposited in the aperture section 66.

That is, the transparent electrodes 54 b ₁ and 54 e made of ITO assumethe role of a pixel electrode to collect electric charges.

The pixel capacitor 14 a is constituted by the underlying pixelelectrode 63 a and the pixel capacitor wire 14 provided thereon.Therefore, an area is set aside on a corner of the underlying pixelelectrode 63 a closest to the drain electrode 53 b so as to accommodatea contact hole 68 a in which electric connection is established betweenthe drain electrode 53 b and the underlying pixel electrode 63 a.Another area is set aside on another corner of the underlying pixelelectrode 63 a opposite to the contact hole 68 a so as to accommodate acontact hole 68 b in which electric connection is established betweenthe drain electrode 53 b and the transparent electrode 54 e deposited inthe other aperture section 66 via the underlying pixel electrode 63 a.

In an active matrix substrate of such a structure, the area occupied bythe aperture section 66 and efficiency in collecting electric chargesremain substantially the same as those in the sixth embodiment. It issafe to say that other advantages of the sixth embodiment discussedearlier are not at all lost in the present embodiment, except that thegate insulation film 42 is patterned so as to form the contact holes 68a and 68 b using a different photomask from the one used in thepatterning of the protection film 45.

Further, the transparent electrode 54 a constituting the signal line 11,the transparent electrodes 54 b ₁ and 54 e as first pixel electrodes,and the transparent electrode 54 c constituting the pixel capacitor wire14 can be fabricated from the same conductive layer through patterningthereof. Hence, the number of steps is reduced, and cost reductions aresuccessfully achieved.

Further, in the structure of the present embodiment, the width of theunderlying pixel electrode 63 a is set shorter than the width of thepixel electrode 63 shown in FIG. 21; therefore, light can pass throughmost part of the pixel. This is convenient when light is projected tothe entirety of the active matrix substrate on its side facing thetransparent substrate 50, i.e., on the side opposite to the side wherean x-ray is projected, so as to refresh the conversion layer.

In other words, due to the nature of the conversion layer, electriccharges may still remain in the conversion layer in small quantitiesafter electric charges are read. These remaining electric chargespossibly degrade signal precision and cause polarization, rendering theconversion layer per se less reliable. Accordingly, in some cases, theconversion layer can be effectively refreshed by projecting light to theconversion layer at a constant cycle, for example, at every intervalbetween read-out frames. When this is the case, the light blockingareas, including the gate electrode and the pixel electrode, arepreferably small, so as to sufficiently irradiate the conversion layerwith the light projected to the entirety of the active matrix substrateon its side facing the transparent substrate 50.

Embodiment 8

Referring to FIG. 24 and FIG. 25, the following description will discussa further embodiment in accordance with the present invention. Here, forconvenience, members of the present embodiment that have the samearrangement and function as members of the previous embodiments, andthat are mentioned in the previous embodiments are indicated by the samereference numerals and description thereof is omitted.

The arrangement of the present embodiment has a feature in that anunderlying pixel electrode 43 a (corresponding to a second pixelelectrode) is provided in place of the pixel electrode 43 shown in FIG.16 and FIG. 17 of the fifth embodiment, and that an overlying pixelelectrode 43 b (corresponding to a first pixel electrode) is disposed onthe underlying pixel electrode 43 a with an interlayer insulation film71 being interposed in between, and also in that the overlying pixelelectrode 43 b is disposed to overlie a signal line 11, a scanning line12, and a pixel capacitor wire 14.

Therefore, the active matrix substrate of the present embodiment employsthe arrangement of the active matrix substrate shown in FIG. 16 and FIG.17 with little modification. Specifically, the underlying pixelelectrode 43 a can assume the function as the foregoing pixel electrode43 only by removing the protection film 45 according to the aperturesection 46 shown in FIG. 16, if the interlayer insulation film 71 andthe overlying pixel electrode 43 b are not provided.

Further, the underlying pixel electrode 43 a corresponds to the “pixelelectrode” in claims which recite, “the storage capacitor is formedbetween the pixel electrode and the storage capacitor electrode”,because the underlying pixel electrode 43 a is a conductive body layerthat is fabricated from the transparent conductive layer 54 throughpatterning thereof and connected to the drain electrode 53 b, and theunderlying pixel electrode 43 a and the pixel capacitor electrode 41constitute a pixel capacitor.

In manufacture, the steps illustrated in FIG. 18( a) through FIG. 18( f)are performed as they are, so as to deposit a protection film 45. Then,the protection film 45 is partly removed so as to form a precursor to acontact hole 72 through which the overlying pixel electrode 43 b iselectrically coupled to the underlying pixel electrode 43 a, and anacrylic photosensitive resin is applied. Subsequently, the precursor tothe contact hole 72 is exposed to light for development, so as tocomplete the formation of the contact hole 72 that passes through theprotection film 45 and the interlayer insulation film 71.

Thereafter, the overlying pixel electrode 43 b made of ITO is depositedto complete the manufacture of an active matrix substrate. The overlyingpixel electrode 43 b is connected through the contact hole 72 to theunderlying pixel electrode 43 a that is a transparent conductive filmextending from a drain electrode 53 b of the TFT 13.

In the present embodiment, the overlying pixel electrode 43 b isdisposed partly overlapping the signal line 11, the scanning line 12,and the pixel capacitor wire 14; therefore, the aperture area is greatlyincreased.

In an image sensor, as mentioned in the foregoing, the area throughwhich light passes does not serve as an aperture section; instead, thearea where a pixel electrode is in contact with a conversion layerserves as an aperture section. Therefore, in the arrangement of thepresent embodiment, substantially the whole area serves as an aperturesection, except the area where a gap 73 is formed in the overlying pixelelectrode 43 b between adjacent pixels (see FIG. 25). Electric chargesgenerated in the conversion layer are collected by the overlying pixelelectrode 43 b at a maximum efficiency.

Besides, the interlayer insulation film 71 is provided in a thickness of3 μm by spin coating; therefore, the surface of the interlayerinsulation film 71 can be formed extremely flat. This enables aconversion layer of a high quality to be formed from amorphous seleniumin a stable manner.

Specifically, when a conversion layer is formed from amorphous selenium,if the underlying layer is not substantially flat, the amorphousselenium crystallizes starting at mounds and dents on the surface of theunderlying layer, and fails to give desired properties to the conversionlayer. By contrast, when the interlayer insulation film 71 is formed byspin coating, the interlayer insulation film 71 covers the mounds anddents and thus flattens the underlying layer; the amorphous selenium isgiven nowhere to start crystallizing. In addition, since the contacthole 72 is formed by photolithography, the contact hole 72 has a smoothedge and does not permit the amorphous selenium to start crystallizingat the contact hole 72.

Note that in the arrangement of the present embodiment, the overlyingpixel electrode 43 b is disposed so as to overlap the signal line 11;however, needless to say, the overlying pixel electrode 43 b ispreferably disposed so as not to overlap the signal line 11 if thepermitivity and thickness of the interlayer insulation film 71 arelikely to excessively increase the electrostatic capacity between theoverlying pixel electrode 43 b and the signal line 11 and thereby tocause an increase in the capacity and noise in the signal line 11.

If the overlying pixel electrode 43 b is disposed so as not to overlapthe signal line 11, the same advantages are still available incomparison to the arrangement of the fifth embodiment where the electriccharges can be collected highly efficiently and the crystallization ofamorphous selenium can be prevented.

As already mentioned above, active matrix substrates with an interlayerinsulation film are applied in conventional liquid crystal displaydevices. The manufacturing process for those liquid crystal displaydevices is applicable to the manufacture of active matrix substrates ofthe present embodiment only by modifying the pattern in the patterning,which results in reduced manufacturing cost.

Incidentally, the arrangement of the present embodiment is applicable toliquid crystal display devices as well as to active matrix substratesfor use in image sensors. However, the pixel capacitor wire 14 and thepixel capacitor electrode 41 are fabricated from a light blocking metallayer; therefore, the arrangement, if applied to liquid crystal displaydevices of a transparent type, is not practical because of too low anaperture ratio (in this case, the ratio of area through which light canpass). Meanwhile, if the arrangement is applied to liquid crystaldisplay devices of a reflective type that are getting increasing demandin the market recently, the existence of the light blocking patternbelow the overlying pixel electrode 43 b does not raise a problem.

Note that if the active matrix substrate of the present embodiment isapplied to a liquid crystal display device of a reflective type,needless to say, the overlying pixel electrode 43 b needs to be madefrom a metal with a high reflectance, such as aluminum, instead of ITO.

Embodiment 9

Referring to FIG. 26 through FIG. 29, the following description willdiscuss a further embodiment in accordance with the present invention.Here, for convenience, members of the present embodiment that have thesame arrangement and function as members of the previous embodiments,and that are mentioned in the previous embodiments are indicated by thesame reference numerals and description thereof is omitted.

An active matrix substrate of the present embodiment is different fromthe active matrix substrate of the seventh embodiment shown in FIG. 23in that the former lacks the aperture section 66, the contact hole 68 band the transparent electrode 54 e, and instead, includes an interlayerinsulation film 71 and an overlying pixel electrode 43 b′ that arestacked, and a contact hole 68 a of the gate insulation film 42 that islocated right below a contact hole 72 a of the interlayer insulationfilm 71, so as to provide electrical connection linking an underlyingpixel electrode 63 a, the overlying pixel electrode 43 b′, and atransparent electrode 54 b ₂.

The transparent electrode 54 b ₂ functions as a connection electrode forelectrically connecting the drain electrode 53 b to the overlying pixelelectrode 43 b′. The pixel capacitor wire 14 is constituted by atransparent electrode 54 c′ and a metal wire 55 c′ correspondingrespectively to the transparent electrode 54 c and the metal wire 55 c.

Therefore, the manufacturing process of the seventh embodiment isapplicable after only slight modification: in the manufacturing stepsfor the active matrix substrate shown in FIG. 23, no contact hole 68 bis formed if the contact hole 68 a is etched out in the gate insulationfilm 42, and no transparent electrode 54 e is formed if the transparentelectrodes 54 a, 54 b ₂, and 54 c′ are formed.

Subsequently, a protection film 45 is formed and partly removed to forma precursor to a contact hole 68 a. Then, similarly to the process inthe eighth embodiment, a contact hole 72 a is formed, in place of thecontact hole 72, in the interlayer insulation film 71 and the overlyingpixel electrode 43 b′.

The active matrix substrate of the present embodiment, if applied toimage sensors, gives the same advantages as those of the foregoingeighth embodiment. Meanwhile, the active matrix of the presentembodiment, if applied to liquid crystal display devices, isadvantageous in its versatility such that it is also applicable totransparent types as well as to reflective types.

This is because a relatively narrow light blocking underlying pixelelectrode 63 a is formed under the pixel capacitor wire 14 so as toconstitute the pixel capacitor 14 a. Thus, light is blocked only by thesignal line 11, the scanning line 12, and the surrounding part of thepixel capacitor wire 14, and an area in the underlying pixel electrode63 a which accommodates the contact hole 68 a; the same level ofaperture ratio is ensured for the pixel as in the active matrixsubstrate using a conventional interlayer insulation film.

Further, a metal layer constituting the signal line 11 and the scanningline 12 is always disposed below the part not covered with the overlyingpixel electrode 43 b, such as the gap 73 (see FIG. 27) between adjacentpixels; therefore, the present embodiment can retain an advantage of theconventional active matrix substrate incorporating an interlayerinsulation film whereby the opposite substrate across the liquid crystalcan dispense with a black matrix. In addition, the present embodimenthas the aforementioned unique advantage imparted by the signal line 11only crossing the scanning line 12.

In the present embodiment, the contact hole 68 a and the contact hole 72a are formed in the same position through the gate insulation film 42,the protection film 45, and the interlayer insulation film 71. Thisarrangement prevents a decrease in the aperture ratio as a result of theprovision of separate light blocking areas where the contact holes 68 aand 72 a are formed respectively, and also enables the underlying pixelelectrode 63 a to block light so as to prevent disturbance in thealignment of the liquid crystal caused by the contact hole 72 a of theinterlayer insulation film 71.

Besides, the arrangement in which the contact hole 68 a and the contacthole 72 a are provided in the same position enables the use of the samephotomask, contributing a reduction in manufacturing costs.

In the foregoing, the gate insulation film 42 is patterned prior to thedeposition of the transparent conductive layer constituting thetransparent electrode 54 b ₂ and the like and the metal layerconstituting the metal wire 55 c and the like. Instead, the gateinsulation film 42 may be patterned simultaneously with the protectionfilm 45 subsequently to the deposition of the protection film 45. Afurther alternative is to pattern the interlayer insulation film 71 andsubsequently pattern the protection film 45 and the gate insulation film42 simultaneously using the patterned interlayer insulation film 71 inplace of a resist without performing a photolithography step.

FIG. 28 and FIG. 29 show the aforementioned preferred structure. FIG. 28is a major part plan view showing only a neighborhood of the a contacthole 72 a′ corresponding to a neighborhood of the contact hole 72 ashown in FIG. 26. FIG. 29 is a cross-sectional view taken along lineN–N′ shown in FIG. 28.

In the structure shown in FIG. 26 and FIG. 27, the protection film 45and the gate insulation film 42, although sharing a common pattern,cannot be simultaneously patterned, because the transparent electrode 54b ₂ is interposed between the protection film 45 and the gate insulationfilm 42. In other words, in order to connect the transparent electrode54 b ₂ to the underlying pixel electrode 63 a, the gate insulation film42 needs to be patterned prior to the deposition of the transparentconductive layer constituting the transparent electrode 54 b ₂ and thelike, so as to form the contact hole 68 a.

By contrast, according to the arrangement shown in FIG. 28 and FIG. 29,the gate insulation film 42 is deposited on the underlying pixelelectrode 63 a, and thereafter the transparent electrode 54 b ₂ ispatterned without performing the patterning step of the gate insulationfilm 42. In other words, the transparent electrode 54 b ₂ is not formedwhere the contact hole 68 a is to be formed. Therefore, bysimultaneously patterning the protection film 45 and the gate insulationfilm 42 using the subsequently patterned interlayer insulation film 71in place of a mask, the protection film 45 is etched in a sizecorresponding to the contact hole 72 a′, while the gate insulation film42 is etched in a size corresponding to the contact hole 68 a which issmaller than the contact hole 72 a′ with the interlayer insulation film71 and the transparent electrode 54 b ₂ serving in place of a mask.

The etching is possible because the protection film 45 and the gateinsulation film 42 are composed of the same material or of materialssharing similar properties (e.g., SiN_(x) or SiO₂), and also aresufficiently different from the transparent electrode 54 b ₂ (e.g., ITO)in the selection ratios of an etchant. Specifically, the protection film45 and the gate insulation film 42 are simultaneously patterned usingbuffered hydrofluoric acid or a similar etchant that does not decomposethe ITO. The etchant therefore selectively remove the gate insulationfilm 42 where the transparent electrode 54 b ₂ exists and where thetransparent electrode 54 b ₂ does not exist.

Thus, a deposition body constituted by the transparent electrode 54 b ₂and the gate insulation film 42 remains unetched in a portion of thecontact hole 72 a′. Meanwhile, in the other portion of the contact hole72 a′, such a deposition body does not exist, leaving the underlyingpixel electrode 63 a being exposed. By providing the overlying pixelelectrode 43 b′ on both of the portions, the transparent electrode 54 b₂ can be electrically connected to the underlying pixel electrode 63 avia the overlying pixel electrode 43 b′. Note that the transparentelectrode 54 b ₂ functions as a connection electrode for electricallyconnecting the drain electrode 53 b to the overlying pixel electrode 43b′.

The simultaneous patterning of the protection film 45 and the gateinsulation film 42, and the possible omission of the photolithographystep by using the interlayer insulation film 71 in place of a resist,reduce the number of steps greatly and thereby enable a great reductionin the manufacturing cost to be achieved.

Embodiment 10

Referring to FIG. 30 and FIG. 31, the following description will discussa further embodiment in accordance with the present invention. Here, forconvenience, members of the present embodiment that have the samearrangement and function as members of the previous embodiments, andthat are mentioned in the previous embodiments are indicated by the samereference numerals and description thereof is omitted.

The active matrix substrate of the present embodiment includes the samearrangement with the active matrix substrate of the ninth embodiment 9shown in FIG. 27, except the pattern of the interlayer insulation film,and accordingly, the manners whereby the overlying pixel electrode isdeposited.

Specifically, the contact hole 72 b is not formed in the interlayerinsulation film 71 a by the same pattern as the contact hole 68 a isformed in the gate insulation film 42. The contact hole 72 b is etchedout larger than the contact hole 72 a shown in FIG. 27 by removing theinterlayer insulation film 71 so as to uncover the contact hole 68 a andthe pixel capacitor wire 14.

In the arrangement, the overlying pixel electrode 43 c and the pixelcapacitor wire 14 constitute an electrostatic capacity across theprotection film 45. Thus, the pixel capacitor wire 14 is flanked by theprotection film 45 and the gate insulation film 42 which are in turnflanked by the overlying pixel electrode 43 c and the underlying pixelelectrode 63 a; therefore, the pixel capacitor 14 a can double itscapacity.

This is because of no other reason but the electrostatic capacityconstituted by the overlying pixel electrode 43 c and the pixelcapacitor wire 14 reinforcing the electrostatic capacity constituted bythe underlying pixel electrode 63 a and the pixel capacitor wire 14.

The protection film 45 is formed by depositing about 3000 Å thicksilicon nitride film that is substantially the same film as the gateinsulation film 42. The electrostatic capacity constituted by theoverlying pixel electrode 43 c and the pixel capacitor wire 14 issubstantially as large as the electrostatic capacity constituted by theunderlying pixel electrode 63 a and the pixel capacitor wire 14.

The pixel capacitor 14 a of the foregoing double layer structureoccupies a reduced area and thus further improves on the aperture ratio,when adopted in an active matrix substrate in a liquid crystal displaydevice. Besides, the double layer structure enables the pixel capacitor14 a to be readily modified and aptly adopted in an image sensor whichneeds an extremely large pixel capacitor.

Besides, in comparison to the conventional manufacturing process of anactive matrix substrate, the steps do not increase in number at all, anddo not need to be fundamentally changed; this enables cheap manufactureof an excellent-performance active matrix substrate, an improvedaperture ratio, a reduced load on the pixel capacitor wire and thesignal line, an increased pixel capacitor, and further advantages.

The following description will present in organized manner, and furtherexplain, functions and effects of arrangements of the active matrixsubstrates in accordance with the present invention.

An active matrix substrate in accordance with the present inventionincorporates all the features of either a first basic arrangement inaccordance with the present invention or a second basic arrangement inaccordance with the present invention, and additionally may be such thatthe storage capacitor electrode is a transparent electrode film,

where the first basic arrangement of an active matrix substrate is suchthat the active matrix substrate includes:

a pixel electrode provided for each pixel constituted by a scanning lineand a signal line that are disposed in a matrix as a whole;

a switching element located near a point where the scanning line crossesthe signal line, so as to be connected to the scanning line, the signalline, and the pixel electrode;

a storage capacitor electrode for constituting a storage capacitor withthe pixel electrode therebetween; and

a storage capacitor common wire disposed parallel to the signal line,wherein

the signal line, the storage capacitor electrode, and the storagecapacitor common wire are fabricated from a single electrode layerthrough patterning thereof, and

the second basic arrangement of an active matrix substrate is such thatthe active matrix substrate includes:

a pixel electrode provided in each pixel area bounded by a scanning lineand a signal line that are disposed in a matrix as a whole;

a switching element connected to the scanning line, the signal line, andthe pixel electrode;

a storage capacitor electrode for constituting a storage capacitor withthe pixel electrode therebetween; and

a storage capacitor common wire disposed parallel to the signal line soas to be connected to the storage capacitor electrode, wherein

the signal line and the storage capacitor electrode are fabricated froma single electrode layer through patterning thereof.

With the foregoing arrangement, the active matrix substrate does notdecrease the aperture ratio of the pixels when incorporated in, forexample, a liquid crystal display device. Besides, if the active matrixsubstrate is used in an image sensor, the light blocking area can bereduced between the transparent substrate and the conversion layer inthe image sensor; therefore, the conversion layer can be refreshedefficiently by the method of projecting light to the entirety of theimage sensor.

If the storage capacitor common wire is also a transparent electrodefilm, the aperture ratio of the pixels is further improved, and theforegoing effects are thereby enhanced.

An active matrix substrate in accordance with the present inventionincorporates all the features of either one of the first and secondbasic arrangements, and additionally may be such that the pixelelectrode is disposed opposing the storage capacitor electrode across aninsulation film for covering the switching element.

With the arrangement, a storage capacitor is constituted by a pixelelectrode, an insulation film covering a switching element, and astorage capacitor electrode. Accordingly, with no additional specialsteps (for example, a step of forming a dielectric layer between a pixelelectrode and a storage capacitor electrode), a storage capacitor can bereadily formed, and active matrix substrates can be manufactured withimproved productivity.

An active matrix substrate in accordance with the present invention maybe such that an interlayer insulation film is interposed between thepixel electrode and the insulation film, and also that the pixelelectrode is disposed opposing the storage capacitor electrode incontact hole formed through the interlayer insulation film.

With the arrangement, an interlayer insulation film, as well as aninsulation film, is interposed between the pixel electrode and theelectrode lines (referring to the scanning line, the signal line, theconnection electrode, and other electrode wires disposed below the pixelelectrode); therefore, the pixel electrode and the electrode lines lessaffect each other. Besides, the dimensions of the storage capacitor arelimited by the dimensions of the contact hole formed through theinterlayer insulation film; therefore, the use of a readily patternedinterlayer insulation film allows easy and precise control on the valueof the storage capacitor.

An active matrix substrate in accordance with the present inventionincorporates all the features of a third basic arrangement in accordancewith the present invention, and additionally may be such that the signalline and the pixel electrode are fabricated from a single conductivelayer through patterning thereof,

where the third basic arrangement of an active matrix substrate is suchthat the active matrix substrate includes:

a pixel electrode provided in each pixel area bounded by a scanning lineand a signal line that are disposed in a matrix as a whole;

a switching element connected to the scanning line, the signal line, andthe pixel electrode;

a storage capacitor electrode for constituting a storage capacitor; and

a storage capacitor common wire disposed parallel to the signal line soas to be connected to the storage capacitor electrode, wherein

the storage capacitor is formed between the pixel electrode and thestorage capacitor electrode, and

the scanning line and the storage capacitor electrode are fabricatedfrom a single electrode layer through patterning thereof.

In the arrangement, the scanning lines are fabricated from the samelayer as the storage capacitor electrode, and the signal lines arefabricated from the same layer as the pixel electrode; therefore, afterconcurrently fabricating the scanning lines and the storage capacitorelectrode, the signal lines and the pixel electrode can be fabricatedconcurrently again. As a result, active matrix substrates that exhibitexcellent performance for the cost expended can be manufactured using adevice for manufacturing conventional active matrix substrates, with asmaller number of steps.

An active matrix substrate in accordance with the present invention, inorder to solve the foregoing problems, may further include an interlayerinsulation film on which the pixel electrode is provided.

With the arrangement, the pixel electrode is provided as a top layer ofthe active matrix, and the pixel electrode can be thereby disposed onthe scanning lines, the signal lines, and the storage capacitor commonwire; therefore, the pixel can be given a greatly increased aperturearea in design. That is, the entire area, except the part required toaccommodate a gap between pixel electrodes of adjacent pixels, can serveas an aperture section for the pixel.

Therefore, the active matrix substrate, if incorporated in an imagesensor by depositing a conversion layer thereon, can collect electriccharges generated in the conversion layer to the pixel electrode at amaximum efficiency, because in the image sensor the area where the pixelelectrode is in contact with the conversion layer serves as the aperturesection for the pixel.

Further, since the aperture ratio of the pixel can be increasedsufficiently, the active matrix substrate is suitably incorporated notonly in an image sensor, but also in a liquid crystal display device.

An active matrix substrate in accordance with the present inventionincorporates all the features of a fourth basic arrangement inaccordance with the present invention, and additionally may be such thatthe signal line and the storage capacitor electrode are fabricated froma single conductive layer through patterning thereof,

where the fourth basic arrangement of an active matrix substrate is suchthat the active matrix substrate includes:

a pixel electrode provided in each pixel area bounded by a scanning lineand a signal line that are disposed in a matrix as a whole;

a switching element connected to the scanning line, the signal line, andthe pixel electrode;

a storage capacitor electrode for constituting a storage capacitor withthe pixel electrode therebetween; and

a storage capacitor common wire disposed parallel to the signal line soas to be connected to the storage capacitor electrode, wherein

the scanning line and the pixel electrode are fabricated from a singleelectrode layer through patterning thereof.

In the arrangement, the scanning lines are fabricated from the sameelectrode layer as is the pixel electrode, and the signal lines arefabricated from the same electrode layer as is the storage capacitorelectrode; therefore, after concurrently fabricating the scanning linesand the pixel electrode, the signal lines and the storage capacitorelectrode can be fabricated concurrently again. As a result, activematrix substrates that exhibit excellent performance for the costexpended can be manufactured using a device for manufacturingconventional active matrix substrates, with a smaller number of steps.

An active matrix substrate in accordance with the present invention maybe such that the conductive layer is patterned so as to cover a pixelaperture section of the pixel electrode.

With the arrangement, the conversion layer can be deposited so as not tobe in direct contact with the pixel electrode; therefore, the pixelelectrode is not necessarily made from a material that is compatiblewith the physical properties of the conversion layer. As a result, thematerial for the electrode layer fabricated into the scanning lines andthe pixel electrode can be chosen from a wider range of selection.Meanwhile, the conductive layer can be made from ITO or other materialsthat are compatible with the physical properties of the conversion layerand capable of forming a surface that hardly deteriorates.

Hence, unlike the case where the conversion layer is deposited directlyon the pixel electrode, no inconvenience is likely to arise where a baresurface of the pixel electrode in the aperture section would be oxidizedand could interrupt a satisfactory level of conductance with theconversion layer.

An active matrix substrate in accordance with the present inventionincorporates all the features of a fifth basic arrangement in accordancewith the present invention, and additionally may be such that the signallines, the first pixel electrode, and the storage capacitor electrodeare fabricated from a single conductive layer through patterningthereof,

where the fifth basic arrangement of an active matrix substrate is suchthat the active matrix substrate includes:

a first pixel electrode provided for each pixel area bounded by ascanning line and a signal line that are disposed in a matrix as awhole;

a switching element connected to the scanning line, the signal line, andthe first pixel electrode;

a second pixel electrode connected to the first pixel electrode;

a storage capacitor electrode for constituting a storage capacitor withthe second pixel electrode therebetween; and

a storage capacitor common wire disposed parallel to the signal line soas to be connected to the storage capacitor electrode, wherein

the scanning line and the second pixel electrode are fabricated from asingle electrode layer through patterning thereof.

In the arrangement, the scanning lines are fabricated from the samelayer as the second pixel electrode, whereas the signal lines, the firstpixel electrode, and the storage capacitor electrode are fabricated fromthe same layer; therefore, after concurrently fabricating the scanninglines and the second pixel electrode, the signal lines, the first pixelelectrode, and the storage capacitor electrode can be fabricatedconcurrently again. As a result, active matrix substrates that exhibitexcellent performance for the cost expended can be manufactured using adevice for manufacturing conventional active matrix substrates, with asmaller number of steps.

An active matrix substrate in accordance with the present invention mayfurther include a connection electrode for connecting the first pixelelectrode to the switching element, wherein

the signal line, the connection electrode, and the storage capacitorelectrode are fabricated from a single conductive layer throughpatterning thereof.

With the arrangement, the first pixel electrode is connected to theswitching element via the connection electrode; therefore, for example,the first pixel electrode can be provided as the top layer with aninsulation layer interposed between the first pixel electrode and theconnection layer. This enables the first pixel electrode to be disposedon the scanning lines, the signal lines, and the storage capacitorcommon wire, and thereby enables the manufacture of an active matrixsubstrate with a greatly increased aperture area for a pixel.

Further, since the scanning lines and the second pixel electrodes arefabricated from a single layer, and the signal lines, the connectionelectrode, and the storage capacitor electrode are also fabricated froma single layer, after concurrently fabricating the scanning lines andthe second pixel electrode, the signal lines, the connection electrode,and the storage capacitor electrode can be fabricated concurrentlyagain. As a result, active matrix substrates that exhibit more excellentperformance for the cost expended can be manufactured using a device formanufacturing conventional active matrix substrates, with a smallernumber of steps.

An active matrix substrate in accordance with the present invention maybe such that the conductive layer allows light to pass therethrough.

With the arrangement, as earlier mentioned, even if the second pixelelectrode blocks light, the second pixel electrode only needs to beprovided in an area sufficient for the formation of a storage capacitor,the area where the second pixel electrode is not provided can contributeto the aperture section of the pixel. It is in this aperture sectionwhere a light-passing conductive layer is deposited; therefore, lightcan also pass through the completed aperture section.

As a result, active matrix substrates can be manufactured that aresuitable for use in liquid crystal display devices of a transparenttype. In addition, if the active matrix substrate is adopted in an imagesensor, a sufficient amount of light can be projected on the conversionlayer from a desired direction to refresh the conversion layer.

An active matrix substrate in accordance with the present invention maybe such that the first pixel electrode and the storage capacitorelectrode constitute the storage capacitor across the protection film.

With the arrangement, the storage capacitor electrode is disposed so asto constitute a storage capacitor with the second pixel electrodetherebetween; therefore, the storage capacity of a pixel can be doubledby arranging the storage capacitor electrode so as to constitute astorage capacitor with the first pixel electrode across the protectionfilm.

As a result, even if the light blocking second pixel electrode is formedin a limited area from the same electrode layer as is the scanning line,a necessary storage capacitor is still available. The active matrixsubstrate including such an arrangement can provide a large aperturearea when incorporated in a liquid crystal display device of atransparent type.

Further, when incorporated in an image sensor which requires anextremely large storage capacitor, the active matrix substrate readilyprovides a storage capacitor of the required level.

An active matrix substrate in accordance with the present invention mayfurther include an interlayer insulation film on which the first pixelelectrode is provided.

With the arrangement, the first pixel electrode is disposed as the toplayer of the active matrix substrate; therefore, the first pixelelectrode can be disposed on the scanning lines, the signal lines, andthe storage capacitor common wire. As a result, the aperture area of thepixel can be set to an greatly increased value. That is, the entire areabetween adjacent pixels, except the part required to accommodate a gapbetween first pixel electrodes, can serve as an aperture section for thepixel.

Hence, if an image sensor is constituted by the foregoing active matrixsubstrate and a conversion layer deposited thereon; the area where thefirst pixel electrode is in contact with the conversion layer serves asan aperture section for a pixel; therefore, in the image sensor, thefirst pixel electrode can collect those electric charges generated inthe conversion layer at a maximum efficiency.

Further, since the aperture ratio of the pixel can be increasedsufficiently, the active matrix substrate is suitably incorporated notonly in an image sensor, but also in a liquid crystal display device.

An active matrix substrate in accordance with the present invention, inorder to solve the problem, may be such that the scanning lines areanodized.

With the arrangement, the scanning lines are insulated from the otherwires with improved reliability. Therefore, active matrix substrates canbe manufactured with improved yields, and it is better ensured thatdefective lines and other such serious display defects are preventedfrom developing from insufficiently insulated scanning lines.

Meanwhile, the storage capacity electrode, the pixel electrode, or thesecond pixel electrode fabricated from the same electrode layer as isthe scanning lines through patterning thereof are preferably notanodized. When this is the case, the insulation layer interposed betweenthe pixel electrode and the capacitor storage electrode constituting thestorage capacitor or the insulation layer interposed between the secondpixel electrode and the capacitor storage electrode constituting thestorage capacitor can have a single layer structure constituted by thegate insulation film. As a result, the permitivity can be increased, andthe electrostatic capacity per unit area can be hence increased,enabling a relatively large supplementary capacity to be obtained for arelatively small area.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art intended tobe included within the scope of the following claims.

1. An active matrix substrate, comprising: a pixel electrode provided ina pixel area; a scanning line and a signal line; a switching elementelectrically connected to the scanning line, the signal line, and thepixel electrode; a storage capacitor electrode for a storage capacitor;and a storage capacitor common line disposed parallel to the signal lineso as to be electrically connected to the storage capacitor electrode,the storage capacitor common line extending across a plurality ofpixels, wherein storage capacitance is provided between the pixelelectrode and the storage capacitor electrode, the scanning line and thestorage capacitor electrode are fabricated from a same material in asingle patterning; and wherein the storage capacitor electrode and thestorage capacitor common line are patterned in different steps so as tohave an insulating film provided partially therebetween, and wherein thegiven storage capacitor electrode does not extend across a plurality ofdifferent pixels.
 2. The active matrix substrate as defined in claim 1,wherein the signal line and the pixel electrode are fabricated from asingle conductive layer through patterning thereof.
 3. The active matrixsubstrate as defined in claim 1, further comprising an interlayerinsulation film on which the pixel electrode is provided.
 4. The activematrix substrate as defined in claim 1, further comprising a gateinsulation film for covering a gate electrode of the switching element,wherein the pixel electrode is disposed opposing the storage capacitorelectrode across the gate insulation film.
 5. The active matrixsubstrate as defined in claim 1, wherein the scanning line is anodized.6. The active matrix substrate of claim 1, wherein a plurality of thestorage capacitor common lines are provided substantially parallel tothe signal line on the active matrix substrate, and wherein theplurality of storage capacitor common lines are provided for a pluralityof columns of pixels, respectively, so that a storage capacitor commonline is provided for each column of pixels in the plurality.
 7. Anactive matrix substrate, comprising: a pixel electrode provided in apixel area; a scanning line and a signal line; a switching elementelectrically connected to the scanning line, the signal line, and thepixel electrode; a storage capacitor electrode for a storage capacitor;and a storage capacitor common line disposed at least partially parallelto the signal line so as to be electrically connected to the storagecapacitor electrode, the storage capacitor common line extending acrossa plurality of pixels, wherein storage capacitance is provided betweenthe pixel electrode and the storage capacitor electrode, and wherein thegiven storage capacitor electrode does not extend across a plurality ofdifferent pixels, the scanning line and the storage capacitor electrodeare fabricated from a same material in a single patterning; and whereinin another patterning the signal line, the pixel electrode, and thestorage capacitor common line are fabricated of a same material in asingle patterning.
 8. The active matrix substrate of claim 7, wherein aplurality of the storage capacitor common lines are providedsubstantially parallel to the signal line on the active matrixsubstrate, and wherein the plurality of storage capacitor common linesare provided for a plurality of columns of pixels, respectively, so thata storage capacitor common line is provided for each column of pixels inthe plurality.
 9. An active matrix substrate, comprising: a pixelelectrode provided in a pixel area; a scanning line and a signal line; aswitching element electrically connected to the scanning line, thesignal line, and the pixel electrode; a storage capacitor electrode fora storage capacitor; and a storage capacitor common line disposed atleast partially parallel to the signal line so as to be electricallyconnected to the storage capacitor electrode, the storage capacitorcommon line extending across a plurality of pixels, and wherein thesignal line and the storage capacitor common line are fabricated of asame material in a single patterning, wherein storage capacitance isprovided between the pixel electrode and the storage capacitorelectrode, and wherein the given storage capacitor electrode does notextend across a plurality of different pixels, the scanning line and thestorage capacitor electrode are fabricated from a same material in asingle patterning; a protection film for covering the switching element;and an interlayer insulation film interposed between the pixel electrodeand the protection film.
 10. The active matrix substrate as defined inclaim 9, wherein a contact hole is formed through the interlayerinsulation film and the protection film so as to electrically connectingthe pixel electrode to the switching element.
 11. The active matrixsubstrate of claim 9, wherein a plurality of the storage capacitorcommon lines are provided substantially parallel to the signal line onthe active matrix substrate, and wherein the plurality of storagecapacitor common lines are provided for a plurality of columns ofpixels, respectively, so that a storage capacitor common line isprovided for each column of pixels in the plurality.
 12. An imagesensor, comprising: an active matrix substrate; a conversion section forconverting incident magnetoelectric radiation to electric charges; andbias voltage application means for causing a storage capacitor to storethe electric charges, wherein the active matrix substrate includes: apixel electrode provided in a pixel area; a scanning line and a signalline; a switching element electrically connected to the scanning line,the signal line, and the pixel electrode; a storage capacitor electrodefor a storage capacitor; and a storage capacitor common line disposed atleast partially parallel to the signal line so as to be electricallyconnected to the storage capacitor electrode, the storage capacitorcommon line extending across a plurality of pixels, wherein the scanningline and the storage capacitor electrode are fabricated from a samematerial in a single patterning; and wherein the storage capacitorelectrode and the storage capacitor common line are patterned indifferent steps so as to have an insulating film provided partiallytherebetween, and wherein the given storage capacitor electrode does notextend across a plurality of different pixels.
 13. The image sensor asdefined in claim 12, further comprising: a gate insulation film forcovering a gate electrode of the switching element; and a conductivebody layer deposited on the gate insulation film so as to be connectedto the switching element, wherein the storage capacitor electrode andthe conductive body layer constitute the storage capacitor across thegate insulation film.
 14. The image sensor as defined in claim 12,wherein the scanning line is anodized.
 15. The active matrix substrateof claim 12, wherein a plurality of the storage capacitor common linesare provided substantially parallel to the signal line on the activematrix substrate, and wherein the plurality of storage capacitor commonlines are provided for a plurality of columns of pixels, respectively,so that a storage capacitor common line is provided for each column ofpixels in the plurality.
 16. An active matrix substrate, comprising: apixel electrode provided in each pixel area bounded by a scanning lineand a signal line that are disposed in a matrix as a whole; a switchingelement connected to the scanning line, the signal line, and the pixelelectrode; a storage capacitor electrode for constituting a storagecapacitor; and a storage capacitor common line disposed parallel to thesignal line so as to be connected to the storage capacitor electrode,the storage capacitor common line extending across a plurality ofpixels, wherein the storage capacitor is formed between the pixelelectrode and the storage capacitor electrode, and wherein the givenstorage capacitor electrode does not extend across a plurality ofdifferent pixels, the scanning line and the storage capacitor electrodeare fabricated from a single electrode layer through patterning thereof,and the signal line and the storage capacitor common line are fabricatedof a same material in a single patterning thereof.
 17. The active matrixsubstrate of claim 16, wherein a plurality of the storage capacitorcommon lines are provided substantially parallel to the signal line onthe active matrix substrate, and wherein the plurality of storagecapacitor common lines are provided for a plurality of columns ofpixels, respectively, so that a storage capacitor common line isprovided for each column of pixels in the plurality.